Remove doubled words from documentation and comments.

Spot candidates by running these commands:
  git ls-files |xargs perl -0777 -n \
    -e 'while (/\b(then?|[iao]n|i[fst]|but|f?or|at|and|[dt]o)\s+\1\b/gims)' \
    -e '{$n=($` =~ tr/\n/\n/ + 1); ($v=$&)=~s/\n/\\n/g; print "$ARGV:$n:$v\n"}'

Thanks to Jim Meyering for the original patch.

doc/lzma-file-format.txt

@@ -40,7 +40,7 @@ The .lzma File Format
 
 0.2. Changes
 
-        Last modified: 2009-05-01 11:15+0300
+        Last modified: 2011-04-12 11:55+0300
 
 
 1. File Format
@@ -161,6 +161,6 @@ The .lzma File Format
         XZ Utils - The next generation of LZMA Utils
         http://tukaani.org/xz/
 
-        The .xz file format - The successor of the the .lzma format
+        The .xz file format - The successor of the .lzma format
         http://tukaani.org/xz/xz-file-format.txt
 

src/liblzma/common/alone_encoder.c

@@ -103,7 +103,7 @@ alone_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 	if (options->dict_size < LZMA_DICT_SIZE_MIN)
 		return LZMA_OPTIONS_ERROR;
 
-	// Round up to to the next 2^n or 2^n + 2^(n - 1) depending on which
+	// Round up to the next 2^n or 2^n + 2^(n - 1) depending on which
 	// one is the next unless it is UINT32_MAX. While the header would
 	// allow any 32-bit integer, we do this to keep the decoder of liblzma
 	// accepting the resulting files.

src/liblzma/lzma/lzma2_encoder.c

@@ -374,7 +374,7 @@ lzma_lzma2_props_encode(const void *options, uint8_t *out)
 	const lzma_options_lzma *const opt = options;
 	uint32_t d = my_max(opt->dict_size, LZMA_DICT_SIZE_MIN);
 
-	// Round up to to the next 2^n - 1 or 2^n + 2^(n - 1) - 1 depending
+	// Round up to the next 2^n - 1 or 2^n + 2^(n - 1) - 1 depending
 	// on which one is the next:
 	--d;
 	d |= d >> 2;

src/xz/file_io.c

@@ -53,7 +53,7 @@ static bool io_write_buf(file_pair *pair, const uint8_t *buf, size_t size);
 extern void
 io_init(void)
 {
-	// Make sure that stdin, stdout, and and stderr are connected to
+	// Make sure that stdin, stdout, and stderr are connected to
 	// a valid file descriptor. Exit immediately with exit code ERROR
 	// if we cannot make the file descriptors valid. Maybe we should
 	// print an error message, but our stderr could be screwed anyway.

src/xz/xz.1

@@ -866,7 +866,7 @@ This is equivalent to specifying \fB\-\-memlimit\-compress=\fIlimit
 \fB\-\-memlimit\-decompress=\fIlimit\fR.
 .TP
 .B \-\-no\-adjust
-Display an error and exit if the compression settings exceed the
+Display an error and exit if the compression settings exceed
 the memory usage limit.
 The default is to adjust the settings downwards so
 that the memory usage limit is not exceeded.

windows/INSTALL-Windows.txt

@@ -133,7 +133,7 @@ Building XZ Utils
 Using a snapshot from the Git repository
 
     To use a snapshot, the build system files need to be generated with
-    autogen.sh or "autoreconf -fi" before trying to build using the the
+    autogen.sh or "autoreconf -fi" before trying to build using the
     above build instructions. You can install the relevant extra packages
     from MinGW or use Cygwin or use e.g. a GNU/Linux system to create a
     source package with the required build system files.