Force shell use when in bash/sh mode

tools/export/gcc_arm_common.tmpl

@@ -4,10 +4,10 @@
 # cross-platform directory manipulation
 ifeq ($(shell echo $$OS),$$OS)
     MAKEDIR = if not exist "$(1)" mkdir "$(1)"
-    RM = rmdir /S /Q
+    RM = rmdir /S /Q "$(1)"
 else
-    MAKEDIR = mkdir -p $(1)
-    RM = rm -rf
+    MAKEDIR = $(SHELL) -c "mkdir -p $(1)"
+    RM = $(SHELL) -c "rm -rf $(1)"
 endif
 
 ifeq (,$(filter .build,$(notdir $(CURDIR))))
@@ -24,7 +24,7 @@ $(OBJDIR): all
 Makefile : ;
 % :: $(OBJDIR) ; :
 clean :
-	$(RM) $(OBJDIR)
+	$(call RM,$(OBJDIR))
 {% block target_clean -%}
 {% endblock %}
 else