Multisampled lines should be rasterized as rectangles, even when we
don't support wide lines (i.e. they are one pixel wide).

Change-Id: I4960ea7347f826b3af1ff6830ebde46d3065aea9
Reviewed-on: https://swiftshader-review.googlesource.com/16008Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>