DMD 32 bit Linux code gen now uses XMM for float & double

[Walter Bright]

32 Bit Linux now uses XMM registers for float and double rather than the x87.

This should substantially speed up routine float and double processing.
SIMD vector operations, however, are still not support on 32 bit Linux code
because of issues with 16 byte stack alignment.

This means that generated code will no longer work on older x86 processors that
do not have XMM registers. If this is an issue, please file a bug report.

https://github.com/dlang/dmd/pull/9895

DMD always had that capability, it just wasn't enabled for backwards 
compatibility with older processors.