Common: Remove gotos in FileUtil, and replace FILE*s with IOFile/ifstreams.
Common: Remove goto in MemArena.
DVDInterface: Tweak speeds
JIT: free up a register by eliminating RCODE_POINTERS

Also use shorter code in the dispatcher if we can get away with it (e.g. on
Windows where the relevant memory is in the low 2GB).
Make WII_IPC_HLE_Device_DI call DVDInterface
GeometryShaderManager: Set stereo parameters in a SetConstants() call.

Doing it in SetProjectionChanged() is too early because the projection type is not set yet.
Merge pull request #1737 from degasus/master

OGL: don't clear the stencil buffer
Merge pull request #1634 from JosJuice/disc-drive-unification-lite

Make WII_IPC_HLE_Device_DI call DVDInterface
Merge pull request #1703 from FioraAeterna/saveregs

JIT: free up a register by eliminating RCODE_POINTERS
Merge pull request #1633 from JosJuice/dvd-speed-tweak

DVDInterface: Tweak speeds
Merge pull request #1486 from rohit-n/goto

Remove some gotos.
Merge pull request #1734 from Armada651/stereo-fixes

GeometryShaderManager: Set stereo parameters in a SetConstants() call.
OGL: Fix OGL3 with stereo enabled