Revert 239423 since it breaks base_unittests in linux, cros, mac valgrind bots.

"""
> Make gtest always use simple internal regex engine.
> 
> In order to allow regex matches in gtest to be shared between Windows and other
> systems, we tell gtest to always use it's internal engine.
> 
> The syntax supported by the internal engine initially looks like a subset of
> POSIX regexs. However character class shortcuts are not valid POSIX.
> 
> Even more confusingly the system POSIX regex function often defines extra
> features not actually part of the standard allowing regex that work on Linux
> fail on Mac OS X.
> 
> A search through the code base did not reveal any locations where features not
> supported by the internal regex engine where used.
> 
> See bug https://code.google.com/p/chromium/issues/detail?id=317224 for more detailed description.
> 
> BUG=317224
> 
> Review URL: https://codereview.chromium.org/55983002

TBR=mithro@mithis.com

Review URL: https://codereview.chromium.org/107853004

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@239679 4ff67af0-8c30-449e-8e8b-ad334ec8d88c