ARM: zImage: Use the right 'size' binary

Some host platforms have native 'size' binaries that cannot grok arm
binaries for some reason.  Check to see if there is a
$(CROSS_COMPILE)size binary available and use that instead.

Change-Id: Ic0dedbad671e10cef70bc5603b8b004d054ad12e
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index 414f8da..2cd81c8 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -120,7 +120,8 @@
 asflags-y := -Wa,-march=all
 
 # Supply kernel BSS size to the decompressor via a linker symbol.
-KBSS_SZ = $(shell size $(obj)/../../../../vmlinux | awk 'END{print $$3}')
+SIZEBIN := $(if $(shell which $(CROSS_COMPILE)size),$(CROSS_COMPILE)size,size)
+KBSS_SZ = $(shell $(SIZEBIN) $(obj)/../../../../vmlinux | awk 'END{print $$3}')
 LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
 # Supply ZRELADDR to the decompressor via a linker symbol.
 ifneq ($(CONFIG_AUTO_ZRELADDR),y)