DSTwo: Add a dummy errno variable. It goes unused, however.
OpenDingux: Center the progress text onto the progress bar itself in the middle of the screen. Also use TRS-80 blue for the background of the progress bar.
OpenDingux: Quick fix to disable most MIPS32 R2 instructions in the stub, but allow the SYNCI instruction.

At least one code block in #ifdef MIPS_32R2/#endif is causing Doom/GBA to suddenly and permanently emit garbled grey images. An example of this bug can be seen here: <http://www.youtube.com/watch?v=cfEPcjt8cV0>.

This is a correctness commit. The performance will be slightly slower with it.