Update prcpucfg.h to build in Native Client.
Update prcpucfg.h to build in Native Client.

Native Client is similar to Linux, but it does not define __linux__.

http://codereview.chromium.org/5479001/



git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@67985 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser