The recent libsanitizer import broke the build on Solaris/SPARC with the
native as:

/usr/ccs/bin/as: ".libs/sanitizer_errno.s", line 4247: error: symbol
"__sanitizer_internal_memset" is used but not defined
/usr/ccs/bin/as: ".libs/sanitizer_errno.s", line 4247: error: symbol
"__sanitizer_internal_memcpy" is used but not defined
/usr/ccs/bin/as: ".libs/sanitizer_errno.s", line 4247: error: symbol
"__sanitizer_internal_memmove" is used but not defined

Since none of the alternatives considered in the PR worked out, this
patch checks if the assembler does support symbol assignment, disabling
the code otherwise.  This returns the code to the way it was up to LLVM 16.

Bootstrapped without regressions on sparc-sun-solaris2.11 (as and gas) and
i386-pc-solaris2.11 (as and gas).

2023-11-23  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	libsanitizer:
	PR sanitizer/112563
	* configure.ac (libsanitizer_cv_as_sym_assign): Check for
	assembler symbol assignment support.
	* configure: Regenerate.
	* asan/Makefile.am (DEFS): Add @AS_SYM_ASSIGN_DEFS@.
	* Makefile.in, asan/Makefile.in, hwasan/Makefile.in,
	interception/Makefile.in, libbacktrace/Makefile.in,
	lsan/Makefile.in, sanitizer_common/Makefile.in, tsan/Makefile.in,
	ubsan/Makefile.in: Regenerate.