[PATCH] uml: use -mcmodel=kernel for x86_64

We have never used this flag and recently one user experienced a complaining
warning about this (there was a symbol in the positive half of the address space
IIRC). So fix it.
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/um/Makefile-x86_64

@@ -4,10 +4,13 @@
 core-y += arch/um/sys-x86_64/
 START := 0x60000000
 
+_extra_flags_ = -fno-builtin -m64 -mcmodel=kernel
+
 #We #undef __x86_64__ for kernelspace, not for userspace where
 #it's needed for headers to work!
-CFLAGS += -U__$(SUBARCH)__ -fno-builtin -m64
-USER_CFLAGS += -fno-builtin -m64
+CFLAGS += -U__$(SUBARCH)__ $(_extra_flags_)
+USER_CFLAGS += $(_extra_flags_)
+
 CHECKFLAGS  += -m64
 AFLAGS += -m64
 LDFLAGS += -m elf_x86_64