mesa: expose AMD_texture_texture4

because the closed driver exposes it. Tested by piglit.

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

src/compiler/glsl/builtin_functions.cpp

@@ -418,6 +418,12 @@ texture_gather_cube_map_array(const _mesa_glsl_parse_state *state)
           state->OES_texture_cube_map_array_enable;
 }
 
+static bool
+texture_texture4(const _mesa_glsl_parse_state *state)
+{
+   return state->AMD_texture_texture4_enable;
+}
+
 static bool
 texture_gather_or_es31(const _mesa_glsl_parse_state *state)
 {
@@ -2891,6 +2897,10 @@ builtin_builder::create_builtins()
                 _texture(ir_txd, shader_texture_lod_and_rect, glsl_type::vec4_type,  glsl_type::sampler2DRectShadow_type, glsl_type::vec4_type, TEX_PROJECT),
                 NULL);
 
+   add_function("texture4",
+                _texture(ir_tg4, texture_texture4, glsl_type::vec4_type, glsl_type::sampler2D_type, glsl_type::vec2_type),
+                NULL);
+
    add_function("textureGather",
                 _texture(ir_tg4, texture_gather_or_es31, glsl_type::vec4_type, glsl_type::sampler2D_type, glsl_type::vec2_type),
                 _texture(ir_tg4, texture_gather_or_es31, glsl_type::ivec4_type, glsl_type::isampler2D_type, glsl_type::vec2_type),