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

This pulls in the following Clang change:

c1f280d: (phosek@chromium.org) Remove Emscripten support

This pulls in the following LLVM change:

21d53da: (phosek@chromium.org) Remove Emscripten support

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

Review URL: https://codereview.chromium.org/1730913002 .

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