Add support for clang:
elfutils seems to exclusively use a gcc extension, nested functions.
clang does not implement this extension, but does have a similar
feature, blocks.
They both function in essentially the same way: closures in C.

Change-Id: I75aba2a37145ef3942d4f1b2019949cfbbdc55a9
Merge remote-tracking branch 'cm/cm-10.1' into cm-10.1-linaro