Update .gitignore
When both _MIPS_ISA and MIPS32R2 undefined #if (_MIPS_ISA==MIPS32R2) gives true and wrong code is being chosen to compile. React only on PSP define which is enough.
Change mode for .gitignore to 644
Introduce output=surface_dingux. Dos screen modes like 640x400x8 and 640x480x8 are downscaled to 320x240, others are blitted with clipping.