Adjust Makefile for LLVM trunk (16) as of 2023-01-05 (#379)

llvm/llvm-project@d227c3b
added __GCC_HAVE_SYNC_COMPARE_AND_SWAP macros.

Makefile

@@ -668,6 +668,7 @@ check-symbols: startup_files libc
 	@# TODO: Undefine __FLOAT128__ for now since it's not in clang 8.0.
 	@# TODO: Filter out __FLT16_* for now, as not all versions of clang have these.
 	@# TODO: Filter out __NO_MATH_ERRNO_ and a few __*WIDTH__ that are new to clang 14.
+	@# TODO: Filter out __GCC_HAVE_SYNC_COMPARE_AND_SWAP_* that are new to clang 16.
 	@# TODO: clang defined __FLT_EVAL_METHOD__ until clang 15, so we force-undefine it
 	@# for older versions.
 	@# TODO: Undefine __wasm_mutable_globals__ and __wasm_sign_ext__, that are new to
@@ -700,6 +701,7 @@ check-symbols: startup_files libc
 	    | sed -e 's/__GNUC_VA_LIST $$/__GNUC_VA_LIST 1/' \
 	    | grep -v '^#define __FLT16_' \
 	    | grep -v '^#define __\(BOOL\|INT_\(LEAST\|FAST\)\(8\|16\|32\|64\)\|INT\|LONG\|LLONG\|SHRT\)_WIDTH__' \
+	    | grep -v '^#define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_\(1\|2\|4\|8\)' \
 	    > "$(SYSROOT_SHARE)/predefined-macros.txt"
 
 	# Check that the computed metadata matches the expected metadata.