General code improvements while trying to use LLVM

[rickgaiser]

I've got to the point where I can compile all IOP modules using LLVM. However, the generated binaries can only be converted to irx using srxfixup irx2 mode that is not compatible with the default loadcore we all use. For now I'm abandoning LLVM attempts on IOP, but I would like to add some of the changes I made to make it work.

Note on IRX1 using old loadcore:
Uses standard MIPS relocation pairs where R_MIPS_HI16 must be immediately followed by its matching R_MIPS_LO16.

Note on IRX2:
Supports more flexible relocation patterns including:

• Standalone R_MIPS_LO16 relocations (without preceding HI16)
• R_MIPS_HI16 not immediately followed by matching R_MIPS_LO16

[uyjulian]

Code changes lgtm