libpayload: fix build

When .xcompile doesn't already exist, building libpayload fails because
the CC variable (et al) remain empty since .xcompile is only included
after the variables coming from there are evaluated.

Change-Id: I73f1cbced95afcff15839604fea5fd05d81bc3d3
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: https://review.coreboot.org/18228
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

payloads/libpayload/Makefile

@@ -107,18 +107,6 @@ ARCH-$(CONFIG_LP_ARCH_ARM64)   := arm64
 ARCH-$(CONFIG_LP_ARCH_X86)     := x86_32
 ARCH-$(CONFIG_LP_ARCH_MIPS)    := mips
 
-CC := $(CC_$(ARCH-y))
-AS := $(AS_$(ARCH-y))
-LD := $(LD_$(ARCH-y))
-NM := $(NM_$(ARCH-y))
-OBJCOPY := $(OBJCOPY_$(ARCH-y))
-OBJDUMP := $(OBJDUMP_$(ARCH-y))
-READELF := $(READELF_$(ARCH-y))
-STRIP := $(STRIP_$(ARCH-y))
-AR := $(AR_$(ARCH-y))
-
-CFLAGS += $(CFLAGS_$(ARCH-y))
-
 # Three cases where we don't need fully populated $(obj) lists:
 # 1. when no .config exists
 # 2. when make config (in any flavour) is run
@@ -149,6 +137,18 @@ $(if $(wildcard .xcompile)$(NOCOMPILE),,$(eval $(shell $(top)/../../util/xcompil
 
 -include .xcompile
 
+CC := $(CC_$(ARCH-y))
+AS := $(AS_$(ARCH-y))
+LD := $(LD_$(ARCH-y))
+NM := $(NM_$(ARCH-y))
+OBJCOPY := $(OBJCOPY_$(ARCH-y))
+OBJDUMP := $(OBJDUMP_$(ARCH-y))
+READELF := $(READELF_$(ARCH-y))
+STRIP := $(STRIP_$(ARCH-y))
+AR := $(AR_$(ARCH-y))
+
+CFLAGS += $(CFLAGS_$(ARCH-y))
+
 ifneq ($(INNER_SCANBUILD),y)
 ifeq ($(CONFIG_LP_COMPILER_LLVM_CLANG),y)
 CC:=clang -m32
@@ -304,12 +304,12 @@ clean-for-update: doxygen-clean clean-for-update-target
 
 clean: clean-for-update clean-target
 	rm -f .ccwrap junit_config junit_config.old
+	rm -rf $(obj)
 
 clean-cscope:
 	rm -f cscope.out
 
-distclean: clean-cscope
-	rm -rf $(obj)
+distclean: clean-cscope clean
 	rm -f .config .config.old ..config.tmp .kconfig.d .tmpconfig* .ccwrap .xcompile junit.xml
 
 .PHONY: $(PHONY) clean clean-cscope cscope distclean doxygen doxy