Added a case to build_config.h to cover compiling for Linux with 16-bit wchars  (alongside the existing cases for Windows with 16-bit wchars and Linux with  32-bit wchars) so that it becomes possible to compile and link the Chromium  base together with third-party libraries that require short wchars. 
Added a case to build_config.h to cover compiling for Linux with 16-bit wchars 
(alongside the existing cases for Windows with 16-bit wchars and Linux with 
32-bit wchars) so that it becomes possible to compile and link the Chromium 
base together with third-party libraries that require short wchars. 

BUG=none
TEST=none
Original review http://codereview.chromium.org/315004
Patch by mdsteele@google.com

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@29786 0039d316-1c4b-4281-b951-d872f2087c98

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