runtime: Fix build failures with -D_FORTIFY_SOURCE=2.

From-SVN: r194116

libgo/runtime/go-signal.c

@@ -144,10 +144,13 @@ static int8 badsignal[] = "runtime: signal received on thread not created by Go.
 static void
 runtime_badsignal(int32 sig)
 {
+	// Avoid -D_FORTIFY_SOURCE problems.
+	int rv __attribute__((unused));
+
 	if (sig == SIGPROF) {
 		return;  // Ignore SIGPROFs intended for a non-Go thread.
 	}
-	runtime_write(2, badsignal, sizeof badsignal - 1);
+	rv = runtime_write(2, badsignal, sizeof badsignal - 1);
 	runtime_exit(1);
 }
 

libgo/runtime/print.c

@@ -18,7 +18,10 @@ gwrite(const void *v, int32 n)
 	G* g = runtime_g();
 
 	if(g == nil || g->writebuf == nil) {
-		runtime_write(2, v, n);
+		// Avoid -D_FORTIFY_SOURCE problems.
+		int rv __attribute__((unused));
+
+		rv = runtime_write(2, v, n);
 		return;
 	}