Reviewed by Mark Rowe.

        Give threads names on platforms with pthread_setname_np.

        * wtf/Threading.cpp:
        (WTF::NewThreadContext::NewThreadContext): Initialize thread name.
        (WTF::threadEntryPoint): Call setThreadNameInternal.
        (WTF::createThread): Pass thread name.

        * wtf/Threading.h: Added new comments, setThreadNameInternal.

        * wtf/ThreadingGtk.cpp:
        (WTF::setThreadNameInternal): Added. Empty.
        * wtf/ThreadingNone.cpp:
        (WTF::setThreadNameInternal): Added. Empty.
        * wtf/ThreadingPthreads.cpp:
        (WTF::setThreadNameInternal): Call pthread_setname_np when available.
        * wtf/ThreadingQt.cpp:
        (WTF::setThreadNameInternal): Added. Empty.
        * wtf/ThreadingWin.cpp:
        (WTF::setThreadNameInternal): Added. Empty.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@41605 268f45cc-cd09-0410-ab3c-d52691b4dbfc