Fix C++11 headers could not be found

* The C++11 standard library contains headers that have underscores. Add
  underscores to `achead:include-patterns'
* Add a space to separate -E and -v in the docstring of
  `achead:include-directories'
Merge pull request #3 from aethanyc/fix-include-patterns

Fix C++11 headers could not be found