i965/vec4: Don't set any dependency control bits for F32TO16 on Gen8.
i965/vec4: Don't set any dependency control bits for F32TO16 on Gen8.

It's expanded to several instructions.

Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler