Add support for ARB_uniform_buffer_object

GLSL Version : >= 120

Purpose:
Allow users to use features by enabling this extension, even in low versions.

Extension Name:
ARB_uniform_buffer_object

Builtin-variables:
Uniform

Builtin-functions:
Nah

Keywords:
Nah

Features:
uniform block

Reference:
https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_uniform_buffer_object.txt

Test/120.vert

@@ -201,3 +201,15 @@ int mac;
 
 #define macr(A,B) A ## B
 int macr(qrs,tuv);
+
+layout(std140) uniform BlockName    // ERROR
+{
+    int test;
+};
+
+#extension GL_ARB_uniform_buffer_object : enable
+
+layout(std140) uniform BlockName
+{
+    int test;
+};

Test/baseResults/120.vert.out

@@ -79,7 +79,8 @@ ERROR: 0:192: 'assign' :  l-value required (can't modify a const)
 ERROR: 0:195: 'gl_ModelViewMatrix' : identifiers starting with "gl_" are reserved 
 ERROR: 0:200: 'token pasting (##)' : not supported for this version or the enabled extensions 
 ERROR: 0:203: 'token pasting (##)' : not supported for this version or the enabled extensions 
-ERROR: 80 compilation errors.  No code generated.
+ERROR: 0:205: '' :  syntax error, unexpected IDENTIFIER
+ERROR: 81 compilation errors.  No code generated.
 
 
 Shader version: 120