The next phase of Mips16 hard float implementation.

Allow Mips16 routines to call Mips32 routines that have abi requirements
that either arguments or return values are passed in floating point 
registers. This handles only the pic case. We have not done non pic
for Mips16 yet in any form.

The libm functions are Mips32, so with this addition we have a complete
Mips16 hard float implementation.

We still are not able to complete mix Mip16 and Mips32 with hard float.
That will be the next phase which will have several steps. For Mips32
to freely call Mips16 some stub functions must be created.

llvm-svn: 173320