Remove FPU availability check, just use the pre-processor flags
to indicicate what the user wanted.
* mips/abiflags.S: New file.
* mips/regs.S (SR_MSA): Define macro.
* mips/mti32.ld: Place .MIPS.abiflags and wrap in marker symbols.
* mips/mti64.ld: Likewise.
* mips/mti64_64.ld: Likewise.
* mips/mti64_n32.ld: Likewise.