Fix selftest FAILs with gdb build with -O2 -flto

diff --git a/gdb/complaints.h b/gdb/complaints.h
index 6ad056d257..cac09ff573 100644
--- a/gdb/complaints.h
+++ b/gdb/complaints.h
@@ -42,9 +42,10 @@ extern int stop_whining;
   while (0)
 
 /* Clear out / initialize all complaint counters that have ever been
-   incremented.  */
+   incremented.  Prevent inlining this function for the benefit of GDB's
+   selftests in the testsuite.  */
 
-extern void clear_complaints ();
+extern void clear_complaints ()  __attribute__((noinline));
 
 
 #endif /* !defined (COMPLAINTS_H) */
diff --git a/gdb/main.c b/gdb/main.c
index 19bbb92388..9d35f9baa8 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -1235,6 +1235,11 @@ captured_main_1 (struct captured_main_args *context)
     }
 }
 
+/* Prevent inlining this function for the benefit of GDB's selftests in the
+   testsuite.  */
+
+static void captured_main (void *data) __attribute__((noinline));
+
 static void
 captured_main (void *data)
 {