BaseTools: Replace ARCH with HOST_ARCH in C Makefile to avoid conflict

https://bugzilla.tianocore.org/show_bug.cgi?id=793

ARCH is too generic. It may cause confuse of target arch or host arch.
To be clarified, replace it with HOST_ARCH in BaseTools C Makefile.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>
(cherry picked from commit a9f6e0a4dc)

BaseTools/Source/C/Makefiles/footer.makefile

@@ -13,12 +13,12 @@
 
 DEPFILES = $(OBJECTS:%.o=%.d)
 
-$(MAKEROOT)/libs-$(ARCH):
-	mkdir -p $(MAKEROOT)/libs-$(ARCH)
+$(MAKEROOT)/libs-$(HOST_ARCH):
+	mkdir -p $(MAKEROOT)/libs-$(HOST_ARCH)
 
 .PHONY: install
-install: $(MAKEROOT)/libs-$(ARCH) $(LIBRARY)
-	cp $(LIBRARY) $(MAKEROOT)/libs-$(ARCH)
+install: $(MAKEROOT)/libs-$(HOST_ARCH) $(LIBRARY)
+	cp $(LIBRARY) $(MAKEROOT)/libs-$(HOST_ARCH)
 
 $(LIBRARY): $(OBJECTS) 
 	$(BUILD_AR) crs $@ $^