i965/fs: Don't mess up stride for uniform integer multiplication.
i965/fs: Don't mess up stride for uniform integer multiplication.

If the stride is 0, the source is a uniform and we should not modify the
stride.

Cc: "10.6" <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91047
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler