intel: Add support for MAX_SAMPLES=1 EXT_framebuffer_multisample.

The spec specifically sets the minimum MAX_SAMPLES at 1 to allow exposing
the extension on all implementations, so do so.

docs/relnotes-7.9.html

@@ -35,6 +35,7 @@ tbd
 <h2>New features</h2>
 <ul>
 <li>GL_EXT_timer_query extension (i965 driver only)
+<li>GL_EXT_framebuffer_multisample extension (intel drivers, MAX_SAMPLES = 1)
 <li>GL_ARB_texture_swizzle extension (alias of GL_EXT_texture_swizzle)
 <li>GL_ARB_draw_elements_base_vertex, GL_ARB_fragment_program_shadow
     and GL_EXT_draw_buffers2 in Gallium drivers

src/mesa/drivers/dri/intel/intel_context.c

@@ -720,6 +720,8 @@ intelInitContext(struct intel_context *intel,
    ctx->Const.MaxPointSizeAA = 3.0;
    ctx->Const.PointSizeGranularity = 1.0;
 
+   ctx->Const.MaxSamples = 1.0;
+
    /* reinitialize the context point state.
     * It depend on constants in __GLcontextRec::Const
     */

src/mesa/drivers/dri/intel/intel_extensions.c

@@ -50,8 +50,9 @@
 #define need_GL_EXT_cull_vertex
 #define need_GL_EXT_draw_buffers2
 #define need_GL_EXT_fog_coord
-#define need_GL_EXT_framebuffer_object
 #define need_GL_EXT_framebuffer_blit
+#define need_GL_EXT_framebuffer_multisample
+#define need_GL_EXT_framebuffer_object
 #define need_GL_EXT_gpu_program_parameters
 #define need_GL_EXT_point_parameters
 #define need_GL_EXT_provoking_vertex
@@ -111,6 +112,7 @@ static const struct dri_extension card_extensions[] = {
    { "GL_EXT_cull_vertex",                GL_EXT_cull_vertex_functions },
    { "GL_EXT_framebuffer_blit",         GL_EXT_framebuffer_blit_functions },
    { "GL_EXT_framebuffer_object",       GL_EXT_framebuffer_object_functions },
+   { "GL_EXT_framebuffer_multisample",    GL_EXT_framebuffer_multisample_functions },
    { "GL_EXT_fog_coord",                  GL_EXT_fog_coord_functions },
    { "GL_EXT_gpu_program_parameters",     GL_EXT_gpu_program_parameters_functions },
    { "GL_EXT_packed_depth_stencil",       NULL },