arch/arm/src/Makefile: dependency directory list is now computed from the VPATH. From Richard Cochran

arch/arm/src/Makefile

@@ -150,7 +150,9 @@ endif
 LIBGCC = "${shell "$(CC)" $(ARCHCPUFLAGS) -print-libgcc-file-name}"
 GCC_LIBDIR := ${shell dirname $(LIBGCC)}
 
-VPATH = chip:common:$(ARCH_SUBDIR)
+VPATH += chip
+VPATH += common
+VPATH += $(ARCH_SUBDIR)
 
 all: $(HEAD_OBJ) $(BIN)
 
@@ -202,7 +204,7 @@ endif
 ifeq ($(BOARDMAKE),y)
 	$(Q) $(MAKE) -C board TOPDIR="$(TOPDIR)" depend
 endif
-	$(Q) $(MKDEP) --dep-path chip --dep-path common --dep-path $(ARCH_SUBDIR) \
+	$(Q) $(MKDEP) $(patsubst %,--dep-path %,$(subst :, ,$(VPATH))) \
 	 "$(CC)" -- $(CFLAGS) -- $(SRCS) >Make.dep
 	$(Q) touch $@