Fix gprof profiling for PRX modules

[fjtrujy]

• Fix gprof profiler to work correctly with PRX (relocatable) modules

  • Convert PC addresses to link-time format in __mcount for proper symbol resolution
  • Maintain backward compatibility with regular (non-PRX) executables

  Problem

  When using gprof with PRX modules loaded via psplink or PPSSPP, the profiler
  produced empty output. PRX modules are relocated at load time, so runtime PC
  addresses don't match the link-time addresses stored in ELF symbols.

  Solution

  Convert addresses to link-time format immediately in __mcount:

  frompc = (frompc & 0x0FFFFFFF) - gp.lowpc;  // link-time = runtime - base
  selfpc = (selfpc & 0x0FFFFFFF) - gp.lowpc;
  
  Since PSP text sections start at address 0 at link-time, this simple
  subtraction gives us the correct addresses for symbol matching.

[sharkwouter]

Works well, thanks!