Update INSTALL.

Add a note about failing "make check". The source of
the problem should be fixed in libtool (if it really is
a libtool bug and not mine) but I'm unable to spend time
on that for now. Thanks to Nelson H. F. Beebe for reporting
the issue.

Add a note about a possible need to run "ldconfig" after
"make install".

INSTALL

@@ -26,6 +26,8 @@ XZ Utils Installation
        4.2. "No POSIX conforming shell (sh) was found."
        4.3. configure works but build fails at crc32_x86.S
        4.4. Lots of warnings about symbol visibility
+       4.5. "make check" fails
+       4.6. liblzma.so (or similar) not found when running xz
 
 
 0. Preface
@@ -463,3 +465,26 @@ XZ Utils Installation
     resulting binaries, but fewer warnings looks nicer and may allow
     using --enable-werror.
 
+
+4.5. "make check" fails
+
+    A likely reason is that libtool links the test programs against
+    an installed version of liblzma instead of the version that was
+    just built. This is obviously a bug which seems to happen on
+    some platforms. A workaround is to uninstall the old liblzma
+    versions first.
+
+    If the problem isn't the one described above, then it's likely
+    a bug in XZ Utils or in the compiler. See the platform-specific
+    notes in this file for possible known problems. Please report
+    a bug if you cannot solve the problem. See README for contact
+    information.
+
+
+4.6. liblzma.so (or similar) not found when running xz
+
+    If you installed the package with "make install" and get an error
+    about liblzma.so (or a similarly named file) being missing, try
+    running "ldconfig" to update the run-time linker cache (if your
+    operating system has such a command).
+