Summary: The mbstring extension is common but not part of the PHP core, and we have a soft dependency on it but generally guard calls with function_exists(). Add the mbstring functions to the whitelist of known extension functions so lint doesn't raise errors about them if you don't have mbstring installed.
Test Plan: @ffx, can you verify this fixes the lint issue for you? Probably faster than recompiling my PHP without mbstring.
Reviewers: ffx, btrahan
Reviewed By: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D2961
Summary: D2728 added some extensions as builtin functions to the symbol map, but users may have old caches which still list these dependencies. Bump the symbol cache version; @nodren reported that dropping caches fixed the issue for him.
Test Plan: Ran "arc lint", got cache rebuilds.
Reviewers: vrana, nodren
Reviewed By: vrana
CC: aran
Maniphest Tasks: T1347
Differential Revision: https://secure.phabricator.com/D2746