Force small lib usage when using uARM tc

Author: theotherjimmy

tools/toolchains/arm.py

@@ -312,6 +312,7 @@ class ARM_MICRO(ARM):
     def __init__(self, target, notify=None, macros=None,
                  silent=False, extra_verbose=False, build_profile=None,
                  build_dir=None):
+        target.default_lib = "small"
         ARM.__init__(self, target, notify, macros, build_dir=build_dir,
                      build_profile=build_profile)
         if not set(("ARM", "uARM")).intersection(set(target.supported_toolchains)):