Move generate_XXX_exception from builtin-functions to thread-info

Summary: These are only used in thread-info.cpp so we can move them there and
make them static.  They're easier to find this way too (I can never remember
they're in builtin-functions since it seems pretty random).

Reviewed By: @jdelong

Differential Revision: D1712143

Signature: t1:1712143:1417493459:9f9dbcecc155fc45e16fff3d63f5646068ab4cbc
touch_variation1 is flaky

Summary: Both it and touch use dirname(__FILE__)."/touch.dat", so they can't be
run concurrently.

Reviewed By: @fredemmott

Differential Revision: D1712418

Signature: t1:1712418:1417546066:e938a29484398ce85cbf5956eacdebfa6210a9ee
Revert work around for gcc compilation issue

Summary: Revert part of commit a7c76ea. The assertion inside bufferSize() failed.

Fixes guzzle test run failure.
Closes https://github.com/facebook/hhvm/pull/4327

Reviewed By: @fredemmott

Differential Revision: D1701516

Signature: t1:1701516:1417556817:2b2668faccb44935edd11a0d2652b7019c457b22