libstdc++: Fix typo in comment in <bits/atomic_wait.h>

libstdc++-v3/ChangeLog:

	* include/bits/atomic_wait.h: Fix typo in comment.

libstdc++-v3/include/bits/atomic_wait.h

diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h
index 5224e69..22fda6d 100644
--- a/libstdc++-v3/include/bits/atomic_wait.h
+++ b/libstdc++-v3/include/bits/atomic_wait.h
@@ -102,7 +102,7 @@
 	  && ((sizeof(_Tp) == 4 && alignof(_Tp) >= 4)
 		|| (sizeof(_Tp) == 8 && alignof(_Tp) >= 8));
 #else
-// define _GLIBCX_HAVE_PLATFORM_WAIT and implement __platform_wait()
+// define _GLIBCXX_HAVE_PLATFORM_WAIT and implement __platform_wait()
 // and __platform_notify() if there is a more efficient primitive supported
 // by the platform (e.g. __ulock_wait()/__ulock_wake()) which is better than
 // a mutex/condvar based wait.