builtin_unreachable is not available for older gcc

ldso/include/dl-syscall.h

@@ -51,7 +51,7 @@ extern int _dl_errno;
 static __always_inline attribute_noreturn __cold void _dl_exit(int status)
 {
 	INLINE_SYSCALL(_dl_exit, 1, status);
-#if defined __GNUC__ && !__GNUC_PREREQ (4, 4)
+#if defined __GNUC__ && (!__GNUC_PREREQ (4, 4) && !__GNUC_PREREQ (4, 2))
 	__builtin_unreachable(); /* shut up warning: 'noreturn' function does return*/
 #else
 	while (1);

libpthread/nptl/forward.c

@@ -160,6 +160,10 @@ FORWARD2(__pthread_unwind,
 		       /* We cannot call abort() here.  */
 		       INTERNAL_SYSCALL_DECL (err);
 		       INTERNAL_SYSCALL (kill, err, 1, SIGKILL);
+#if defined __GNUC__ && (!__GNUC_PREREQ (4, 4) && !__GNUC_PREREQ (4, 2))
 		       __builtin_unreachable();
+#else
+			while(1);
+#endif
 		     })
 #undef return