mips: implemented convuwl
mips: use the same function to implement copyl, copyw and copyb
mips: added emit for mov.s
mips: modified copyl to support floats
mips: added _emit() for mov.d
mips: implemented copyq
tests: compile with float support in orc_test_gcc_compile_mips()
mips: factor a bit the code of 'fmt' instructions
mips: factored code of addf and addd
mips: removed defines for emit_add_* since they are not used
mips: added _emit method for float division and multiplication
mips: implemented divf, divd, mulf and muld operations