run-command: add braces for "if" block in wait_or_whine()

Add braces to an "if" block in the wait_or_whine() function. This
isn't needed now, but will make a subsequent commit easier to read.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/run-command.c b/run-command.c
index ea4d0fb..00e68f3 100644
--- a/run-command.c
+++ b/run-command.c
@@ -551,8 +551,9 @@
 
 	while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 		;	/* nothing */
-	if (in_signal)
+	if (in_signal) {
 		return 0;
+	}
 
 	if (waiting < 0) {
 		failed_errno = errno;