Don't translate idx when JitEnableRenameFunctions is set

Users are supposed to be able to override idx with
their own version - but that doesn't work if we translate it
during bytecode emission.

We don't really have a good way of knowing whether its been
overridden, however, so use JitEnableRenameFunctions as we
have for other, similar cases.

Reviewed By: @dariorussi

Differential Revision: D1078332
Avoid calling smart_malloc() to allocate 0 bytes in Vector

Some of the logic in the Vector implementation was unnecessarily calling
into smart_malloc() to allocate 0 bytes, which is wasteful. This diff fixes
the issue appropriately.

Reviewed By: anietoro

Differential Revision: D1079298
Move unique stubs to 'a'

Some of these may actually be hot, and they're small enough that
putting them in 'a' shouldn't hurt.

Reviewed By: @jdelong

Differential Revision: D1069482
Move Collection interface to the HH namespace

Closes #1003
https://github.com/facebook/hhvm/issues/1003

Reviewed By: anietoro

Differential Revision: D1079642
Parse fatal for Interface method bodies

Generate a parse-time fatal for interface methods with method bodies.

Reviewed By: @hermanventer

Differential Revision: D1062389
Fix OSX warning

Fix OSX warning due to mismatched printf type

Reviewed By: @alexmalyshev

Differential Revision: D1078484
Fix OS X segfault on startup

Fix crash due to maybePop() call reading garbage out of the freelist the first time it is accessed.

Closes #1300

Reviewed By: @jdelong

Differential Revision: D1078982
Fix crash trying to inline after a bad method call

In some cases, we can statically prove that an FCall will
go to a particular method. But that might depend on the fact that
the FPush* would fatal. eg we know that an object is of class Foo,
or is null. The FPushObjMethodD will fatal if its null, so the
FCall is known to call Foo::method (or an override).

But if we try to inline the FCall bad things will happen if the
FPush* was interped. So don't do that.

Reviewed By: @swtaarrs

Differential Revision: D1078789