Scripts: Put /usr/xpg4/bin to the beginning of PATH on Solaris.

This adds a configure option --enable-path-for-scripts=PREFIX
which defaults to empty except on Solaris it is /usr/xpg4/bin
to make POSIX grep and others available. The Solaris case had
been documented in INSTALL with a manual fix but it's better
to do this automatically since it is needed on most Solaris
systems anyway.

Thanks to Daniel Richard G.

INSTALL

@@ -123,8 +123,11 @@ XZ Utils Installation
     as an argument to the configure script.
 
     test_scripts.sh in "make check" may fail if good enough tools are
-    missing from PATH (/usr/xpg4/bin or /usr/xpg6/bin). See sections
+    missing from PATH (/usr/xpg4/bin or /usr/xpg6/bin). Nowadays
-    4.5 and 3.2 for more information.
+    /usr/xpg4/bin is added to the script PATH by default on Solaris
+    (see --enable-path-for-scripts=PREFIX in section 2), but old xz
+    releases needed extra steps. See sections 4.5 and 3.2 for more
+    information.
 
 
 1.2.6. Tru64
@@ -443,6 +446,23 @@ XZ Utils Installation
                 and should work on most systems. This has no effect on the
                 resulting binaries.
 
+    --enable-path-for-scripts=PREFIX
+                If PREFIX isn't empty, PATH=PREFIX:$PATH will be set in
+                the beginning of the scripts (xzgrep and others).
+                The default is empty except on Solaris the default is
+                /usr/xpg4/bin.
+
+                This can be useful if the default PATH doesn't contain
+                modern POSIX tools (as can be the case on Solaris) or if
+                one wants to ensure that the correct xz binary is in the
+                PATH for the scripts. Note that the latter use can break
+                "make check" if the prefixed PATH causes a wrong xz binary
+                (other than the one that was just built) to be used.
+
+                Older xz releases support a different method for setting
+                the PATH for the scripts. It is described in section 3.2
+                and is supported in this xz version too.
+
 
 2.1. Static vs. dynamic linking of liblzma
 
@@ -515,11 +535,17 @@ XZ Utils Installation
 
 3.2. PATH
 
+    The method described below is supported by older xz releases.
+    It is supported by the current version too, but the newer
+    --enable-path-for-scripts=PREFIX described in section 2 may be
+    more convenient.
+
     The scripts assume that the required tools (standard POSIX utilities,
-    mktemp, and xz) are in PATH; the scripts don't set the PATH themselves.
+    mktemp, and xz) are in PATH; the scripts don't set the PATH themselves
-    Some people like this while some think this is a bug. Those in the
+    (except as described for --enable-path-for-scripts=PREFIX). Some
-    latter group can easily patch the scripts before running the configure
+    people like this while some think this is a bug. Those in the latter
-    script by taking advantage of a placeholder line in the scripts.
+    group can easily patch the scripts before running the configure script
+    by taking advantage of a placeholder line in the scripts.
 
     For example, to make the scripts prefix /usr/bin:/bin to PATH:
 
@@ -593,8 +619,9 @@ XZ Utils Installation
     some tools are missing from the current PATH or the tools lack
     support for some POSIX features. This can happen at least on
     Solaris where the tools in /bin may be ancient but good enough
-    tools are available in /usr/xpg4/bin or /usr/xpg6/bin. One fix
+    tools are available in /usr/xpg4/bin or /usr/xpg6/bin. For possible
-    for this problem is described in section 3.2 of this file.
+    fixes, see --enable-path-for-scripts=PREFIX in section 2 and the
+    older alternative method described in section 3.2 of this file.
 
     If tests other than test_scripts.sh fail, a likely reason is that
     libtool links the test programs against an installed version of

configure.ac

@@ -516,6 +516,32 @@ case $enable_sandbox in
 esac
 
 
+###########################
+# PATH prefix for scripts #
+###########################
+
+# The scripts can add a prefix to the search PATH so that POSIX tools
+# or the xz binary is always in the PATH.
+AC_ARG_ENABLE([path-for-scripts],
+	[AS_HELP_STRING([--enable-path-for-scripts=PREFIX],
+		[If PREFIX isn't empty, PATH=PREFIX:$PATH will be set in
+		the beginning of the scripts (xzgrep and others).
+		The default is empty except on Solaris the default is
+		/usr/xpg4/bin.])],
+	[], [
+		case $host_os in
+			solaris*) enable_path_for_scripts=/usr/xpg4/bin ;;
+			*)        enable_path_for_scripts= ;;
+		esac
+	])
+if test -n "$enable_path_for_scripts" && test "x$enable_path_for_scripts" != xno ; then
+	enable_path_for_scripts="PATH=$enable_path_for_scripts:\$PATH"
+else
+	enable_path_for_scripts=
+fi
+AC_SUBST([enable_path_for_scripts])
+
+
 ###############################################################################
 # Checks for programs.
 ###############################################################################

src/scripts/xzdiff.in

@@ -15,6 +15,7 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 
+@enable_path_for_scripts@
 #SET_PATH - This line is a placeholder to ease patching this script.
 
 # Instead of unsetting XZ_OPT, just make sure that xz will use file format

src/scripts/xzgrep.in

@@ -18,6 +18,7 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 
+@enable_path_for_scripts@
 #SET_PATH - This line is a placeholder to ease patching this script.
 
 # Instead of unsetting XZ_OPT, just make sure that xz will use file format

src/scripts/xzless.in

@@ -15,6 +15,7 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 
+@enable_path_for_scripts@
 #SET_PATH - This line is a placeholder to ease patching this script.
 
 # Instead of unsetting XZ_OPT, just make sure that xz will use file format

src/scripts/xzmore.in

@@ -15,6 +15,7 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 
+@enable_path_for_scripts@
 #SET_PATH - This line is a placeholder to ease patching this script.
 
 # Instead of unsetting XZ_OPT, just make sure that xz will use file format