Fix r15-8073 (Pass -macos_version_min to the linker)

Fix r15-8073 (Pass -macos_version_min to the linker)

With r15-8073-g952e17223d3a98, gcc_cv_ld64_macosx_version_min is being
used for the replacement and being set in a few locations but
gcc_cv_ld64_macos_version_min is set in others.
Since the auto-host.h variable is named LD64_HAS_MACOS_VERSION_MIN,
I changed over to remove the x from the name.

Committed as obvious after a quick test to make sure LD64_HAS_MACOS_VERSION_MIN
was not set to empty.

gcc/ChangeLog:

	* configure: Regenerate.
	* configure.ac: s/gcc_cv_ld64_macosx_version_min/gcc_cv_ld64_macos_version_min/.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>