glsl: Recognise image memory qualifiers in GLSL ES 3.1.

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

src/glsl/glsl_lexer.ll

@@ -406,11 +406,11 @@ image2DShadow           KEYWORD(130, 300, 0, 0, IMAGE2DSHADOW);
 image1DArrayShadow      KEYWORD(130, 300, 0, 0, IMAGE1DARRAYSHADOW);
 image2DArrayShadow      KEYWORD(130, 300, 0, 0, IMAGE2DARRAYSHADOW);
 
-coherent	KEYWORD_WITH_ALT(420, 300, 420, 0, yyextra->ARB_shader_image_load_store_enable, COHERENT);
-volatile	KEYWORD_WITH_ALT(110, 100, 420, 0, yyextra->ARB_shader_image_load_store_enable, VOLATILE);
-restrict	KEYWORD_WITH_ALT(420, 300, 420, 0, yyextra->ARB_shader_image_load_store_enable, RESTRICT);
-readonly	KEYWORD_WITH_ALT(420, 300, 420, 0, yyextra->ARB_shader_image_load_store_enable, READONLY);
-writeonly	KEYWORD_WITH_ALT(420, 300, 420, 0, yyextra->ARB_shader_image_load_store_enable, WRITEONLY);
+coherent       KEYWORD_WITH_ALT(420, 300, 420, 310, yyextra->ARB_shader_image_load_store_enable, COHERENT);
+volatile       KEYWORD_WITH_ALT(110, 100, 420, 310, yyextra->ARB_shader_image_load_store_enable, VOLATILE);
+restrict       KEYWORD_WITH_ALT(420, 300, 420, 310, yyextra->ARB_shader_image_load_store_enable, RESTRICT);
+readonly       KEYWORD_WITH_ALT(420, 300, 420, 310, yyextra->ARB_shader_image_load_store_enable, READONLY);
+writeonly      KEYWORD_WITH_ALT(420, 300, 420, 310, yyextra->ARB_shader_image_load_store_enable, WRITEONLY);
 
 atomic_uint     KEYWORD_WITH_ALT(420, 300, 420, 310, yyextra->ARB_shader_atomic_counters_enable, ATOMIC_UINT);