PNaCl: Update llvm revision in pnacl/COMPONENT_REVISIONS
PNaCl: Update llvm revision in pnacl/COMPONENT_REVISIONS

This pulls in the following LLVM changes:

452464b: (dschuff@chromium.org) Remove PrefixPass from X86MCNaClSFIState and use EmitRaw instead
8d38037: (dominickd@google.com) MCNaClExpander class + plumbing

BUG=none
TEST= PNaCl toolchain trybots
R=jfb@chromium.org

Review URL: https://codereview.chromium.org/1245463002 .

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