Makefile: turn on USE_ST_TIMESPEC for FreeBSD

Fixes broken compilation on FreeBSD 6.1.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -713,6 +713,7 @@ ifeq ($(uname_S),FreeBSD)
 	BASIC_CFLAGS += -I/usr/local/include
 	BASIC_LDFLAGS += -L/usr/local/lib
 	DIR_HAS_BSD_GROUP_SEMANTICS = YesPlease
+	USE_ST_TIMESPEC = YesPlease
 	THREADED_DELTA_SEARCH = YesPlease
 	ifeq ($(shell expr "$(uname_R)" : '4\.'),2)
 		PTHREAD_LIBS = -pthread