Allow support target name suffix to be customized 

This will allow targets to be generated where spaces aren't desirable in target names. 

Patch by Daniel Wagner-Hall <danielwh@google.com>

Review URL: https://codereview.chromium.org/181433011/


git-svn-id: http://gyp.googlecode.com/svn/trunk@1861 78cadc50-ecff-11dd-a971-7dbc132099af