libgfx: Merge in very early release.

libgfx: Merge in very early release.

This additional library (that gets linked in with the
cart's ELF, rather than libn64) will provide accelerated
graphics functionality.

It currently provides a ucode which can render RDP triangle
commands from 3 vertices in the ucode's vertex buffer.

None of this would would have been possible without krom's
and GreaseMonkey's invaluable help in reverse enginering
"how to triangle" (from below). krom also provided a sample
program which I used extensively while designing the RSP
ucode.

https://forums.cen64.com/viewtopic.php?f=14&t=237

Signed-off-by: Tyler J. Stachecki <stachecki.tyler@gmail.com>