kbuild: HEAD replaced with head-y

In arch/$(ARCH)/Makefile the objects to be linked as the very first are specified with HEAD.
To make more consistent naming, and to allow smarter kbuild style declarations
HEAD is replaced with head-y.
Support for the old notaion is kept for now.
Only i386 updated.

Makefile

@@ -299,12 +299,12 @@ export MODLIB
 #       normal descending-into-subdirs phase, since at that time
 #       we cannot yet know if we will need to relink vmlinux.
 #	So we descend into init/ inside the rule for vmlinux again.
-
-vmlinux-objs := $(HEAD) $(init-y) $(core-y) $(libs-y) $(drivers-y) $(net-y)
+head-y += $(HEAD)
+vmlinux-objs := $(head-y) $(init-y) $(core-y) $(libs-y) $(drivers-y) $(net-y)
 
 quiet_cmd_vmlinux__ = LD      $@
 define cmd_vmlinux__
-	$(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) $(HEAD) $(init-y) \
+	$(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) $(head-y) $(init-y) \
 	--start-group \
 	$(core-y) \
 	$(libs-y) \

arch/i386/Makefile

@@ -75,7 +75,7 @@ mcore-$(CONFIG_X86_SUMMIT)  := mach-default
 # default subarch .h files
 mflags-y += -Iinclude/asm-i386/mach-default
 
-HEAD := arch/i386/kernel/head.o arch/i386/kernel/init_task.o
+head-y := arch/i386/kernel/head.o arch/i386/kernel/init_task.o
 
 libs-y 					+= arch/i386/lib/
 core-y					+= arch/i386/kernel/ \