We need _GNU_SOURCE even when dmapi is not there.

cc -O2 -g -m32 -mtune=ultrasparc -fPIC -DLIB_STRING=\"lib64\"
-c -o uevent.o uevent.c
uevent.c: In function 'uevent_listen':
uevent.c:262: error: invalid application of 'sizeof' to
incomplete type 'struct ucred'
uevent.c:290: error: dereferencing pointer to incomplete type
uevent.c:291: error: dereferencing pointer to incomplete type

---
 libmultipath/Makefile |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: multipath-tools-0.4.8/libmultipath/Makefile
===================================================================
--- multipath-tools-0.4.8.orig/libmultipath/Makefile
+++ multipath-tools-0.4.8/libmultipath/Makefile
@@ -16,8 +16,9 @@ OBJS = memory.o parser.o vector.o devmap
 
 LIBDM_API_FLUSH = $(shell if test -d /lib64 ; then objdump -T /lib64/libdevmapper.so* ; else objdump -T /lib/libdevmapper.so.* ; fi | grep -c dm_task_no_flush)
 
+CFLAGS += -D_GNU_SOURCE
 ifneq ($(strip $(LIBDM_API_FLUSH)),0)
-	CFLAGS += -DLIBDM_API_FLUSH -D_GNU_SOURCE
+	CFLAGS += -DLIBDM_API_FLUSH
 endif
 
 all: $(LIBS)