Remove Toran Proxy support

Summary: We're not using it, as it doesn't cache enough to improve our reliablity. Replaced with --cache-dir.

Reviewed By: @JoelMarcey

Differential Revision: D1561742
Make Framework::installDependencies() final, add <<Override>> where appropriate

Summary: The new hooks mean there's no need to override installDependencies(), and implementing the hook makes it clearer what's going on.

Add <<Override>> to isInstalled just for future safety.

Reviewed By: @JoelMarcey

Differential Revision: D1561812
Reserve / fix error codes.

Summary: Reserve error codes for an upcoming commit.

Also fix one instance of overlapping error codes.

Reviewed By: @elgenie

Differential Revision: D1563423
Tune pcre cache lookup

Summary: In the AHM for pcre cache, optimistically check for
StringData pointer equality before doing a full
comparison.

Reviewed By: @edwinsmith

Differential Revision: D1557919
Clean up const type inference

Summary: Remove duplicated code dealing with infering the type of constants. For
some reason it was doing munging during naming, which we don't need at
all; move the one relevant bit into the other code in declaration. Add a
comment as to why we need special logic here.

Originally to support negative constants:
These are parsed as a unary minus. Fixing here seemed easier
than fixing the parser (which isn't necessarily wrong depending on how
you look at it).

Reviewed By: @int3, @elgenie

Differential Revision: D1559026
Added a rule to the simplifier for LdCtx to constant fold when inlined

Summary: When compiling LateBoundCls, we emit a LdCtx followed by a LdClsCtx to
get the Class that we're operating on. When LateBoundCls is inlined in such a
way where we statically know which Class the callee was invoked with, we can
constant fold the LdCtx and LdClsCtx, which then allows us to DCE the
DefInlineFP and other associated boilerplate for reifying an inline call frame.

Reviewed By: @jdelong

Differential Revision: D1552775