test: Fix path used in AC_CONFIG_AUX_DIR 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>