um: don't bother trying to rebuild CHECKFLAGS for USER_OBJS

... just strip NOSTDINC_FLAGS out of it for those
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/scripts/Makefile.rules

@@ -9,8 +9,6 @@ USER_OBJS := $(foreach file,$(USER_OBJS),$(obj)/$(file))
 
 $(USER_OBJS:.o=.%): \
 	c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) -include user.h $(CFLAGS_$(basetarget).o)
-$(USER_OBJS) : CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ \
-	-Dunix -D__unix__ -D__$(SUBARCH)__ $(CF)
 
 # These are like USER_OBJS but filter USER_CFLAGS through unprofile instead of
 # using it directly.
@@ -18,8 +16,9 @@ UNPROFILE_OBJS := $(foreach file,$(UNPROFILE_OBJS),$(obj)/$(file))
 
 $(UNPROFILE_OBJS:.o=.%): \
 	c_flags = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS)) $(CFLAGS_$(basetarget).o)
-$(UNPROFILE_OBJS) : CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ \
-	-Dunix -D__unix__ -D__$(SUBARCH)__ $(CF)
+
+$(USER_OBJS) $(UNPROFILE_OBJS): \
+	CHECKFLAGS := $(patsubst $(NOSTDINC_FLAGS),,$(CHECKFLAGS))
 
 # The stubs can't try to call mcount or update basic block data
 define unprofile