Add builtin explicitly sized 8, 16, 32, 64 and 128 bit int and

Add builtin explicitly sized 8, 16, 32, 64 and 128 bit int and
unsigned types.
Specify size of r5900 FSR using 32 bit unsigned type.
Correctly format mips registers when some are not 64 bits in size
Check that REGISTER_{RAW,VIRTUAL}_SIZE are consistent when the target
specifies that no conversion is needed when moving from one to the
other.