[optimizing compiler] Add REM_FLOAT and REM_DOUBLE

- for arm, x86, x86_64 backends
- reinstated fmod quick entry points for x86. This is a partial revert
of bd3682ea which added inline assembly
for floting point rem on x86. Note that Quick still uses the inline
version.
- fix rem tests for longs

Change-Id: I73be19a9f2f2bcf3f718d9ca636e67bdd72b5440