Roll libvpx to r291625.

Picks up:
r291620 vpx: Simplify intrinsic gypi files.
r291625 Attempt to let libvpx's SSE files build with clang-cl.

BUG=82385
TBR=tomfinegan@chromium.org

Review URL: https://codereview.chromium.org/502323002

Cr-Commit-Position: refs/heads/master@{#291827}

DEPS

@@ -37,7 +37,7 @@ vars = {
   # After changing nacl_revision, run 'glient sync' and check native_client/DEPS
   # to update other nacl_*_revision's.
   'libaddressinput_revision': 'b52a2aeb63a28914850f3ed81cd7fd26ecdd4cdc', # from svn revision 333
-  'libvpx_revision': 'ace65784417788374f0b19ce5a8abd06c9ccd007',
+  'libvpx_revision': '563c46bb2d0e5d5c8b7d2c6c0c50f0283e9087de', # r291625
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '76db31a2ca11da4dd45016e964b2e49f39f3dd49',
   # Three lines of non-changing comments so that