add support for a prebuilt clang

Change-Id: I07c1725bec1600d7082ff3b57d0b82820eb408a1
build: new clang features

Change-Id: I3eec5c93125937a2d6b84adba6193ec3d8668422
Merge pull request #4 from bart452/kk44

Merge snapdragon llvm clang