PR gcov-profile/77378
	PR gcov-profile/77466
	* libgcov-profiler.c: Use __GCC_HAVE_SYNC_COMPARE_AND_SWAP_{4,8} to
	conditionaly enable/disable *_atomic functions.
	PR gcov-profile/77378
	PR gcov-profile/77466
	* tree-profile.c (tree_profiling): Detect whether target can use
	-fprofile-update=atomic.
	PR gcov-profile/77378
	PR gcov-profile/77466
	* gcc.dg/profile-update-warning.c: New test.

From-SVN: r240008