Remove global std::strings from fileutils.

This is forbidden by the style guide and can cause the static
initialization order fiasco.

BUG=
TEST=test_support_unittests

Review URL: http://webrtc-codereview.appspot.com/248006

git-svn-id: http://webrtc.googlecode.com/svn/trunk@846 4adac7df-926f-26a2-2b94-8c16560cd09d
2 files changed