Complete float support for ceil/floor/trunc.

  Now, we could run through SciMark benchmark, but the performance is a bit weird.

  TILE-Gx Luajit AOVI score, the bigger the better is:

    FFT         1.72  [1024]
    SOR         4.52  [100]
    MC          1.17
    SPARSE      3.03  [1000, 5000]
    LU          2.84  [100]

    SciMark     2.65  [small problem sizes]

  tranditional Lua score is:

    FFT         2.04  [1024]
    SOR         4.51  [100]
    MC          1.37
    SPARSE      2.77  [1000, 5000]
    LU          3.05  [100]

    SciMark     2.75  [small problem sizes]

  AOVI is even slower than tranditional Lua in some cases !  While On
x86-64, AOVI is 5x faster than Lua, We need to figure out why.