This allows test calls to produce output with \n
line separators on Windows, instead of \r\n.
Reduces the number of ifdefs, since all checks
can be done against one template on all platforms.
Assume all supported platforms implement C90, and therefore they
(correctly) implement atexit(), memmove(), setlocale(), strerror(),
and vprintf(), and have <float.h> and <limits.h>.
(Also remove the configure check testing that "do ... while (0)" works
correctly; the non-do/while-based version of G_STMT_START and
G_STMT_END was removed years ago, but the check remained. Also, remove
some checks that configure.ac claimed were needed for libcharset, but
aren't actually used.)
Note that removing the g_memmove() function is not an ABI break even
on systems where g_memmove() was previously not a macro, because it
was never marked GLIB_AVAILABLE_IN_ALL or listed in glib.symbols, so
it would have been glib-internal since 2004.
https://bugzilla.gnome.org/show_bug.cgi?id=710519
This allows compilation with clang without errors, even when
-Wformat-nonliteral is active (as long as there are no real cases of
non literal formatting).
https://bugzilla.gnome.org/show_bug.cgi?id=691608
glib/tests/test-printf tests some non-standard printf formats on
Windows, which gcc doesn't recognize, and so complains about. Disable
those warnings for that test.
https://bugzilla.gnome.org/show_bug.cgi?id=688109
