Change version number to 1.2.7.1.
Replace use of unsafe string functions with snprintf if available.

This avoids warnings in OpenBSD that apparently can't be turned
off whenever you link strcpy, strcat, or sprintf.  When snprintf
isn't available, the use of the "unsafe" string functions has
always in fact been safe, since the lengths are all checked before
those functions are called.

We do not use strlcpy or strlcat, since they are not (yet) found on
all systems.  snprintf on the other hand is part of the C standard
library and is very common.
Avoid including stddef.h on Windows for Z_SOLO compile [Niessink].
Fix gzgetc undefine when Z_PREFIX set [Turk].
Eliminate use of mktemp in Makefile (not always available).
Fix bug in 'F' mode for gzopen().
Add inflateGetDictionary() function.
Correct comment in deflate.h.
Use _snprintf for snprinf in Microsoft C.

More than a decade later, Microsoft C does not support the C99
standard.  It's good that _snprintf has a different name, since it
does not guarantee that the result is null terminated, as does
snprintf.  However where _snprintf is used under Microsoft C, the
destination string is assured to be long enough, so this will not
be a problem.  This occurs in two places, both in gzlib.c.  Where
sprintf functionality is needed by gzprintf, vsnprintf is used in
the case of Microsoft C.
Use _snprintf for snprintf under Microsoft C in test/minigzip.c.
On Darwin, only use /usr/bin/libtool if libtool is not Apple.

The original change was to always use /usr/bin/libtool on Darwin,
in order to avoid using a GNU libtool installed by the user in the
path ahead of Apple's libtool.  However someone might install a
more recent Apple libtool ahead of /usr/bin/libtool.  This commit
checks to see if libtool is Apple, and uses /usr/bin/libtool if it
isn't.
Cleaner check for whether libtool is Apple or not on Darwin.
Delete "--version" file if created by "ar --version" [Richard G.].
Fix configure check for veracity of compiler error return codes.

There were two problems before that this fixes.  One was that the
check for the compiler error return code preceded the determination
of the compiler and its options.  The other was that the checks
for compiler and library characteristics could be fooled if the
error options were set to reject K&R-style C.  configure now aborts
if the compiler produces a hard error on K&R-style C.

In addition, aborts of configure are now consistent, and remove
any temporary files.
Fix CMake compilation of static lib for MSVC2010 x64.
Update copyright year in win32/zlib1.rc.
Fix comment typos in unzip.h and unzip.c.
Remove unused variable in infback9.c.
Fix argument checks in gzlog_compress() and gzlog_write().
Clean up the usage of z_const and respect const usage within zlib.

This patch allows zlib to compile cleanly with the -Wcast-qual gcc
warning enabled, but only if ZLIB_CONST is defined, which adds
const to next_in and msg in z_stream and in the in_func prototype.
A --const option is added to ./configure which adds -DZLIB_CONST
to the compile flags, and adds -Wcast-qual to the compile flags
when ZLIBGCCWARN is set in the environment.