PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS

This pulls in the following LLVM change:

b276efd: (dschuff@chromium.org) Fix NaCl's default to .init_array for constructors

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4120
TEST= PNaCl toolchain trybots
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/986503003
1 file changed