https://github.com/voidlinux/xbps-packages/issues/412

--- Makefile.orig	2014-05-21 12:47:46.915833131 +0200
+++ Makefile	2014-05-21 12:48:54.027409879 +0200
@@ -126,6 +126,8 @@ EXTRA_CFLAGS       += -I$(src)/src/wl/sy
 EXTRA_CFLAGS       += -I$(src)/src/shared/bcmwifi/include
 #EXTRA_CFLAGS       += -DBCMDBG_ASSERT
 
+EXTRA_CFLAGS       += -Wno-date-time
+
 EXTRA_LDFLAGS      := $(src)/lib/wlc_hybrid.o_shipped
 
 KBASE              ?= /lib/modules/`uname -r`
