x86: move i386 and x86_64 Makefiles to arch/x86

Moving the ARCH specific Makefiles for i386 and x86_64
required a litle bit tweaking in the top-lvel Makefile.

SRCARCH is now set in the top-level Makefile
because we need this info to include the correct
arch Makefile.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 2a47290..8816060 100644
--- a/Makefile
+++ b/Makefile
@@ -196,6 +196,9 @@
 UTS_MACHINE 	:= $(ARCH)
 SRCARCH 	:= $(ARCH)
 
+# for i386 and x86_64 we use SRCARCH equal to x86
+SRCARCH := $(if $(filter x86_64 i386,$(SRCARCH)),x86,$(SRCARCH))
+
 KCONFIG_CONFIG	?= .config
 
 # SHELL used by kbuild
@@ -418,7 +421,7 @@
 # Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
 # KBUILD_DEFCONFIG may point out an alternative default configuration
 # used for 'make defconfig'
-include $(srctree)/arch/$(ARCH)/Makefile
+include $(srctree)/arch/$(SRCARCH)/Makefile
 export KBUILD_DEFCONFIG
 
 config %config: scripts_basic outputmakefile FORCE
@@ -497,7 +500,7 @@
 KBUILD_CFLAGS	+= -O2
 endif
 
-include $(srctree)/arch/$(ARCH)/Makefile
+include $(srctree)/arch/$(SRCARCH)/Makefile
 
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls