Replace gcc variadic macro extension with C99 version

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/apb_pci.c b/hw/apb_pci.c
index 36ecb55..d6ce9f4 100644
--- a/hw/apb_pci.c
+++ b/hw/apb_pci.c
@@ -33,10 +33,10 @@
 //#define DEBUG_APB
 
 #ifdef DEBUG_APB
-#define APB_DPRINTF(fmt, args...) \
-do { printf("APB: " fmt , ##args); } while (0)
+#define APB_DPRINTF(fmt, ...) \
+do { printf("APB: " fmt , ## __VA_ARGS__); } while (0)
 #else
-#define APB_DPRINTF(fmt, args...)
+#define APB_DPRINTF(fmt, ...)
 #endif
 
 typedef target_phys_addr_t pci_addr_t;