MIPS procinfo improvements:
- Removed TMIPSProcInfo.needs_frame_pointer, it duplicates pi_needs_stackframe flag.
- Don't save RA for leaf procedures.
* GP is caller-saved register, it does not need saving/restoring as nonvolatile registers. Handle its restore position as a "normal" temp, whose offset is known before secondpass. This allows to handle PIC calls without involving GAS macro processing.


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23885 3ad0048d-3df7-0310-abae-a5850022a9f2