draw: check for line_width != 1.0f in validate_pipeline()

draw: check for line_width != 1.0f in validate_pipeline()

We shouldn't use the wide line stage if the line width is 1.
This check isn't strictly needed because all drivers are (now)
specifying a line wide threshold of at least 1.0 pixels, but
let's play it safe.

Reviewed-by: Charmaine Lee <charmainel@vmware.com>