SPU LLVM: rewrite comparison on non-xfloat path of CFLTU, CFLTS

[elad335]

There was a typo with float comparison type (unordered makes negative Nan result to true, writing -1 instead of 0) in CFLTU.
While also make CFLTU on non-xfloat path accurate as xfloat path now.

Other improvements:

• optimize PPU FCTIW. (unoptimized form was given from thought of non-existing corner case)

[Xcedf]

This PR fixes one hidden issue, normaly it's not an issue on master, but on custom build if i use
non-accurate or approximate version of FMA with non-accurate version of FM i see this in TLoU

now fixed