nvc0: program smooth line width when multisampling is enabled

There are separate line widths for smooth and aliased lines. The smooth
one is selected when multisampling is enabled even if line smoothing
isn't explicitly turned on.

Fixes the ext_framebuffer_multisample-line-smooth piglits

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>

src/gallium/drivers/nouveau/nvc0/nvc0_state.c

@@ -234,7 +234,7 @@ nvc0_rasterizer_state_create(struct pipe_context *pipe,
     SB_IMMED_3D(so, MULTISAMPLE_ENABLE, cso->multisample);
 
     SB_IMMED_3D(so, LINE_SMOOTH_ENABLE, cso->line_smooth);
-    if (cso->line_smooth)
+    if (cso->line_smooth || cso->multisample)
        SB_BEGIN_3D(so, LINE_WIDTH_SMOOTH, 1);
     else
        SB_BEGIN_3D(so, LINE_WIDTH_ALIASED, 1);