libgomp: fix hang on fatal error

Don't try to clean up if a fatal error occurs in libgomp.  Typically the
cleanup is not reentrant so we end up hung on a lock.

libgomp/ChangeLog:

	* error.c (gomp_vfatal): Use abort instead of exit.

diff --git a/libgomp/error.c b/libgomp/error.c
index 50ed85eedb1..25548c14a82 100644
--- a/libgomp/error.c
+++ b/libgomp/error.c
@@ -77,7 +77,7 @@ void
 gomp_vfatal (const char *fmt, va_list list)
 {
   gomp_verror (fmt, list);
-  exit (EXIT_FAILURE);
+  abort ();
 }
 
 void