Exercise the x86 and x86-64 FILD and FISTP instructions.

Exercise the x86 and x86-64 FILD and FISTP instructions.

- Ensure the double- and quadword x87 (FPU) instructions for
  integer loading (resp. fildl and fildll) are properly
  generated by the x86 and x86-64 generators (resp.
  X86Assembler::filds/X86_64Assembler::filds and
  X86Assembler::fildl/X86_64Assembler::fildl).
- Ensure the double- and quadword x87 (FPU) instructions for
  integer storing & popping (resp. filstpl and fistpll) are
  properly generated by the x86 and x86-64 generators (resp.
  X86Assembler::fistps/X86_64Assembler::fistps and
  X86Assembler::fistpl/X86_64Assembler::fistpl).

These instructions can be used in the implementation of the
long-to-float and long-to-double Dex type conversions.

Change-Id: Iade52a9aee326d189d77d3dbd352a2b5dab52e46