PNaCl: Update LLVM revision in pnacl/DEPS
PNaCl: Update LLVM revision in pnacl/DEPS

This pulls in the following LLVM changes:

263d9c7: (mseaborn@chromium.org) PNaCl ABI: Convert "private" linkage to "internal"
8dd5d09: (mseaborn@chromium.org) PNaCl ABI: Disallow the "available_externally" linkage type

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3495
TEST=PNaCl toolchain trybots

Review URL: https://codereview.chromium.org/17115008

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11556 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client