update mkdir to be cross-platform

tools/export/gcc_arm_common.tmpl

@@ -1,6 +1,12 @@
 # This file was automagically generated by mbed.org. For more information, 
 # see http://mbed.org/handbook/Exporting-to-GCC-ARM-Embedded
 
+ifeq ($(OS),Windows_NT)
+	MAKEDIR = mkdir
+else
+	MAKEDIR = mkdir -p
+endif
+
 ifeq (,$(filter bin,$(notdir $(CURDIR))))
 .SUFFIXES:
 OBJDIR := bin
@@ -8,7 +14,7 @@ MAKETARGET = $(MAKE) --no-print-directory -C $@ -f $(CURDIR)/Makefile \
 		SRCDIR=$(CURDIR) $(MAKECMDGOALS)
 .PHONY: $(OBJDIR) clean
 $(OBJDIR):
-	+@[ -d $@ ] || mkdir -p $@
+	+@$(MAKEDIR) $@
 	+@$(MAKETARGET)
 Makefile : ;
 % :: $(OBJDIR) ; :
@@ -68,6 +74,7 @@ else
   CC_FLAGS += -DNDEBUG -Os
 endif
 
+
 .PHONY: all lst size
 
 {% block target_all -%}
@@ -76,21 +83,21 @@ all: $(PROJECT).bin $(PROJECT).hex size
 
 
 .asm.o:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@)
+	@$(MAKEDIR) $(dir $@)
 	$(CC) $(CPU) -c $(ASM_FLAGS) -o $@ $<
 .s.o:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@)
+	@$(MAKEDIR) $(dir $@)
 	$(CC) $(CPU) -c $(ASM_FLAGS) -o $@ $<
 .S.o:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@)
+	@$(MAKEDIR) $(dir $@)
 	$(CC) $(CPU) -c $(ASM_FLAGS) -o $@ $<
 
 .c.o:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@)
+	@$(MAKEDIR) $(dir $@)
 	$(CC)  $(CC_FLAGS) $(CC_SYMBOLS) $(INCLUDE_PATHS) -o $@ $<
 
 .cpp.o:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@)
+	@$(MAKEDIR) $(dir $@)
 	$(CPP) $(CPPC_FLAGS) $(CC_SYMBOLS) $(INCLUDE_PATHS) -o $@ $<