glsl: Emit mul instead of dot if only one component left.
glsl: Emit mul instead of dot if only one component left.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85683
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85691
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler