d3d: Migrate a few more things into common code.
d3d: Centralize framebuf creation/switch logic.
Move FBO_OLD_AGE to the common header.

Guess it's fine here.
d3d: Don't statically import Direct3DCreate9Ex().
d3d: Fix drawpixels texture.
Merge pull request #6869 from unknownbrackets/d3d9

d3d: Centralize more framebuffer management