x86: enable "make ARCH=x86"

After unification of the Kconfig files and
introducing K64BIT support in kconfig
it required only trivial changes to enable
"make ARCH=x86".

With this patch you can build for x86_64 in several ways:
1) make ARCH=x86_64
2) make ARCH=x86 K64BIT=y
3) make ARCH=x86 menuconfig
   => select 64-bit

Likewise for i386 with the addition that
i386 is default is you say ARCH=x86.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
diff --git a/Makefile b/Makefile
index b32963a..9c9c4bf 100644
--- a/Makefile
+++ b/Makefile
@@ -200,9 +200,11 @@
 # Additional ARCH settings for x86
 ifeq ($(ARCH),i386)
         SRCARCH := x86
+        K64BIT  := n
 endif
 ifeq ($(ARCH),x86_64)
         SRCARCH := x86
+        K64BIT  := y
 endif
 
 KCONFIG_CONFIG	?= .config
@@ -339,7 +341,7 @@
 KERNELVERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
 
 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
-export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
+export ARCH SRCARCH K64BIT CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP MAKE AWK GENKSYMS PERL UTS_MACHINE
 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS