[x86] FPU stack needs to be reset after double conversion

The x86 codegen uses the FPU stack for double/float to long conversions. We
need to clear out the FPU stack after done, to prevent an eventual stack
overflow.

Change-Id: I2f306d7c228ad3da2b84faf9f08326769a9417af
Signed-off-by: Udayan Banerji <udayan.banerji@intel.com>
4 files changed