SYS___pthread_markcancel is sometimes used by libwebrtc
<rdar://problem/53408606>
Created attachment 374786 [details] Patch
Comment on attachment 374786 [details] Patch r=me
Comment on attachment 374786 [details] Patch Clearing flags on attachment: 374786 Committed r247782: <https://trac.webkit.org/changeset/247782>
All reviewed patches have been landed. Closing bug.