vpx_thread: use InitializeCriticalSectionEx if available
vpx_thread: use InitializeCriticalSectionEx if available

BUG=b/29583578

original webp change:

commit 63fadc9ffacc77d4617526a50c696d21d558a70b
Author: James Zern <jzern@google.com>
Date:   Mon Nov 23 20:38:46 2015 -0800

    thread: use InitializeCriticalSectionEx if available

    Windows Vista / Server 2008 and up

    Change-Id: I32c5b4e5384d614c5a821ef511293ff014c67966

100644 blob f84207d89b3a6bb98bfe8f3fa55cad72dfd061ff src/utils/thread.c
100644 blob 840831185502d42a3246e4b7ff870121c8064791 src/utils/thread.h

Change-Id: I9ce49b3a86857267e504cd8ceab503b7b441d614

Topopiccione/libvpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,Topopiccione/libvpx,Topopiccione/libvpx,webmproject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,ShiftMediaProject/libvpx,mwgoldsmith/vpx,ShiftMediaProject/libvpx,webmproject/libvpx,mwgoldsmith/vpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,mwgoldsmith/libvpx,webmproject/libvpx,mwgoldsmith/vpx,Topopiccione/libvpx,mwgoldsmith/vpx,webmproject/libvpx,Topopiccione/libvpx