builtin-pack-objects.c: avoid bogus gcc warnings

These empty statement marcos can solicit bogus "statement with no effect"
warnings; squelch them.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index b126fc8e727f8f9670ba85d9a5bf498f1baf5dfc..a15906bdb2021e68a014344cad4e73e9de3367ca 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1311,12 +1311,12 @@ static pthread_mutex_t progress_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 #else
 
-#define read_lock()            0
-#define read_unlock()          0
-#define cache_lock()           0
-#define cache_unlock()         0
-#define progress_lock()                0
-#define progress_unlock()      0
+#define read_lock()            (void)0
+#define read_unlock()          (void)0
+#define cache_lock()           (void)0
+#define cache_unlock()         (void)0
+#define progress_lock()                (void)0
+#define progress_unlock()      (void)0
 
 #endif