AC_CONFIG_AUX_DIRS is an undocumented, internal version of
AC_CONFIG_AUX_DIR that takes a whitespace-separated list, instead of a
single path to add to the list. It also does not automatically treat
the given path as being relative to the $srcdir, unlike the documented
AC_CONFIG_AUX_DIR.
Newer versions of autoconf treat the argument to AC_CONFIG_AUX_DIRS
as being literal (they do not expand the shell variable), causing
autoreconf to fail if $srcdir is explicitly specified. The argument to
AC_CONFIG_AUX_DIR is checked relative to $srcdir anyway, so there is no
need to specify $srcdir a second time.
Resolves: https://github.com/libsdl-org/SDL/issues/4719
Signed-off-by: Simon McVittie <smcv@debian.org>
configure output is practically unchanged. there are still lots of
AC_TRY_COMPILE/AC_TRY_LINK replacements needed to really eliminate
the warnings, but that's for another time.