mips: fix endianess issues

[carenas]

Addresses the remaining issues shown in little endian systems:

carenasgm@gcc23:~/src/sljit$ bin/sljit_test
Pass -v to enable verbose, -s to disable this hint.

test58 case 1 failed
test59 case 5 failed
test77 case 7 failed
test79 case 21 failed
SLJIT tests: 4 (3%) tests FAILED on MIPS III 32bit (little endian + aligned) (with fpu)

[zherczeg]

Is this patch done?

[carenas]

Is this patch done?

yes; I would mark it as draft if it was still being worked on, or have not been tested.

but somehow the previous push (which was done after testing and which I thought was final) had a typo introduced which required an update, several hours later.

at least it was caught earlier, but IMHO this would be a good reason why some sort of CI would be useful.

[zherczeg]

LGTM