macOS: fix host build, SHM names and createBlob failures; add presubmit job#151

jovemexausto wants to merge 4 commits into

google:maingoogle/gfxstream:mainfrom

jovemexausto:capivara/macos-shm-fixjovemexausto/gfxstream:capivara/macos-shm-fixCopy head branch name to clipboard