[mips32][PIC32-MAXI-WEB] generate iHEX
As a consequence .rom_data section was moved to program memory
[mips32] make devcfg variables constant so xc32's linker can mark the section with 'alloc' flag
[mips32] correctly initialize .data section for the xc32 output
[mips32][PIC32-MAXI-WEB] avoid extra aligning to save some memory