i915g: Add draw point sprites.

It's not that much work; hopefully blend func separate also works and we get GL 2.0 for real.

src/gallium/drivers/i915/i915_context.c

@@ -173,6 +173,7 @@ i915_create_context(struct pipe_screen *screen, void *priv)
 
    draw_install_aaline_stage(i915->draw, &i915->base);
    draw_install_aapoint_stage(i915->draw, &i915->base);
+   draw_enable_point_sprites(i915->draw, TRUE);
 
    /* augmented draw pipeline clobbers state functions */
    i915_init_fixup_state_functions(i915);

src/gallium/drivers/i915/i915_screen.c

@@ -109,6 +109,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_ANISOTROPIC_FILTER:
    case PIPE_CAP_DEPTHSTENCIL_CLEAR_SEPARATE:
    case PIPE_CAP_NPOT_TEXTURES:
+   case PIPE_CAP_POINT_SPRITE:
    case PIPE_CAP_PRIMITIVE_RESTART: /* draw module */
    case PIPE_CAP_TEXTURE_MIRROR_REPEAT:
    case PIPE_CAP_TEXTURE_SHADOW_MAP:
@@ -118,8 +119,6 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    /* Features that should be supported (boolean caps). */
    /* XXX: Just test the code */
    case PIPE_CAP_BLEND_EQUATION_SEPARATE:
-   /* XXX: No code but hw supports it */
-   case PIPE_CAP_POINT_SPRITE:
       /* Also lie about these when asked to (needed for GLSL / GL 2.0) */
       return is->debug.lie ? 1 : 0;