Add support for `fallback' to vasm-arm

Summary: code-gen-arm can generate this instruction, which just aborts the
process right now.

Reviewed By: @bertmaher

Differential Revision: D1707290

Signature: t1:1707290:1417041764:d0fb4e0e1611af800add18984946b04e9c018dfc
Remove IRREGULAR_INSTRS and PSUEDOINSTRS

Summary: Normalize how everything calls hhbc-translator, so we can generate it.
Some of the blockers to doing this earlier are gone (inlining is no longer in
ir-translator), so most of this is just straight-forward; the one bummer is
some bits of information are still only available in NormalizedInstruction
right now, so we have to make HhbcTranslator have access to it on each
bytecode.  We can gradually weed that out later.

Reviewed By: @swtaarrs

Differential Revision: D1701003
Use OPCODES instead of REGULAR_INSTRS

Summary: Now that everything is supported we don't need a separate macro to
generate this.

Reviewed By: @alexmalyshev

Differential Revision: D1701007
Remove IRTranslator

Reviewed By: @alexmalyshev

Differential Revision: D1701009
Automatically look up Ids for AA and SA args

Reviewed By: @alexmalyshev

Differential Revision: D1701011
Remove translator-instrs.h, expand macros at only remaining use site

Reviewed By: @swtaarrs

Differential Revision: D1701013
Move interpone-related code to hhbc-translator-interpone.cpp

Reviewed By: @swtaarrs

Differential Revision: D1701443
Make HhbcTranslator not (effectively) a global variable

Summary: Clean up stuff slightly, so that HhbcTranslator's lifetime is
associated with a lexical scope.  Also fix a few easy things that were members
of Translator for no apparent reason.

Reviewed By: @bertmaher

Differential Revision: D1702328

Signature: t1:1702328:1416944361:d42a042f42e1fed4817ce14d878eb2adc463a516
Make translateRegion not a member of a Translator::

Summary: This seemed easy enough but I'm leaving the rest of mcg and tx alone
for now (I'm trying to de-monolithify HhbcTranslator, not these ;)

Reviewed By: @alexmalyshev

Differential Revision: D1702341

Signature: t1:1702341:1416879534:b6692222517fa5ebf68ddb085f7695a00d7cb4ea
Move MInstrEffects to its own .{h,cpp}

Reviewed By: @alexmalyshev

Differential Revision: D1707003

Signature: t1:1707003:1417041990:52bbdbd615384a1508e1193ef9e0fb6b14cb142f