Copy only a screen's worth of pixels from FBO to output

Fixes #2308 (the rest of it), at least for Tales of Destiny 2 and Star Ocean (Valkyrie Profile still has issues but they seem different.)  It also corrects the size in Shadow of Destiny and Wild Arms XF, but you still can't see things in those...

Of course, Star Ocean still doesn't show the character with buffered rendering on in towns, but Tales of Destiny 2 needs buffered rendering enabled if you want to be able to read dialog text.

From my tests, the displayed (screen) region is always the top left 480x272 of what's pointed to by `sceDisplaySetFrameBuf()`.  It might be good to test this in GTA first, but I tested a few other games and they weren't affected by it.

Also fixes a typo I noticed.  There's no good reason to assume render-to-texture is ever full alpha.

-[Unknown]