Fix quant/dequant table bug

1<<31 is not 2^31 because 1 is a signed int in C; this bug affected both the
JIT and interpreter quantized store implementations, though I don't know if
any games were actually affected.
JIT: Don't assume the reserved bits in GQRs are zero

While the unused bits in the GQR SPR are probably not supposed to be set, some
games set them anyways (e.g. Dirt 2), which broke the JIT code.
Merge pull request #731 from FioraAeterna/fixquanttable

Fix quant/dequant table bug
Merge pull request #736 from FioraAeterna/fixdirt

JIT: Don't assume the reserved bits in GQRs are zero
VertexLoader: do not prepare for vertices if we need to skip them
Merge pull request #739 from delroth/vertex-loader-fix

VertexLoader: do not prepare for vertices if we need to skip them

Fixes issue [7542](https://code.google.com/p/dolphin-emu/issues/detail?id=7542)
Merge remote-tracking branch 'upstream/master' into D3D_TEV_Intel_Fix