Clang/Mac: also deploy the header resources.

Change-Id: I0c7abe70dd45216d15a9a62d87c0fda8105cf9a8
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Win/Lin deployqt: fix check for LLVM_INSTALL_DIR

os.environ["LLVM_INSTALL_DIR"] throws an exception if the key is not in
the dictionary.

Change-Id: I0e9dc9dbaf5612db3c530a436161211b6f0351af
Reviewed-by: Eike Ziller <eike.ziller@digia.com>