Fix double-inlining bug w/ singleton inlining

Summary: My singleton inlining machinery assumed that the regular inliner could
never inline singleton patterns.  If this is false, we'll sometimes
inline a function twice, which appears to be happening in practice in
perflab.

I'll try to move the singleton stuff into the new inlining machinery
that I have diffs up for now.

Reviewed By: @bertmaher

Differential Revision: D1412015
Revert "put args in backtrace"

Summary: This reverts commit 6c73c78506536f309dc2445c4b525266008b0823.

D1408391 breaks flib/storage/tao/error/__tests__/TaoClientErrorsTest.php

Reviewed By: @jdelong

Differential Revision: D1414048
JIT on OSX

Summary: As discussed with @ptarjan, these don't fix the JIT entirely (though you can now do a JITted ``echo 1`` on OSX), but these are fine to land on their own.
Closes #2945

Reviewed By: @ptarjan

Differential Revision: D1401501

Pulled By: @LiraNuna