Add ability to treat keywords as identifiers in versions that had not yet reserved the keyword.

Used this for precision keywords and double matrix keywords.

Also added a few missing reserved words.

Also removed redundant "syntax error" when there is a parse error.


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@20423 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/120.frag

@@ -1,10 +1,10 @@
 #version 120
 
-lowp vec3 a;
-mediump float b;
-highp int c;
+float lowp;
+float mediump;
+float highp;
 
-precision highp float;
+float precision;
 
 in vec4 i;
 out vec4 o;