* TCGMIPS.a_load_reg_reg: reduce code duplication, and don't generate same register move for OS_32->OS_S32 and vice versa. Such moves explode into at least 4 instructions if register needs spilling, after which they are no longer recognized and cannot be removed by reg.allocator. So it's much better not to generate them in first place.
* Implemented overflow checking for multiplication, no longer generate MULO and MULOU macros.


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24894 3ad0048d-3df7-0310-abae-a5850022a9f2