Add ss/sd suffix to InstX8632Store and legalize FP constants.

Add ss/sd suffix to InstX8632Store and legalize FP constants.

InstX8632Store is essentially a "mov" and it would emit
a mov, but it did not add the ss/sd suffix based on the operand type.

Also, there are some cases where legalization would leave
two memory operands in the case that one of them
is a floating point immediate:

storeDoubleConst:
.LstoreDoubleConst$entry:
  mov     eax, dword ptr [esp+4]
  mov     qword ptr [eax], qword ptr [L$double$1]
  ret

BUG=none
R=stichnot@chromium.org, wala@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=5a13f45

[Jim Stichnoth, 2014-06-17 23:53:57]

lgtm

[wala, 2014-06-18 00:57:10]

lgtm

[jvoung (off chromium), 2014-06-18 17:42:09]

Committed patchset #2 manually as r5a13f45 (presubmit successful).