Rebuild Xiph libs and include PDB files.

Rebuild the Xiph libs with PDB generation enabled for all
configurations.

BUG=https://code.google.com/p/webm/issues/detail?id=890

Change-Id: Id29cb80e9f01538da041dc8f3801e618914cd608
Add VPx Decoder filter.

Merges the features of the VP8 and VP9 decoder filters into
a single filter.

Change-Id: I98cf86350aa1e5d4741c755c6c88b7cd2f5a9d37
update_xiph_libs.sh: Install pdb files with libs.

Also silences warning related to EditAndContinue being enabled
for some configs (Dshow and MF builds use /SAFESEH, so
any use of EditAndContinue emits a warning).

BUG=https://code.google.com/p/webm/issues/detail?id=890

Change-Id: I7b350db0086e12ed9ef7e31d528a557f54bb1f8d
Merge "Add VPx Decoder filter."
Merge "update_xiph_libs.sh: Install pdb files with libs."