Reasonably safe changes.

Using accessor for vertexbuffer in LLFace
Extra occlusion query lookup in llgl (unused)
Const changes.

indra/llrender/llglslshader.cpp

@@ -717,10 +717,21 @@ GLint LLGLSLShader::getUniformLocation(const string& uniform)
 			return iter->second;
 		}
 	}
-
 	return -1;
 }
 
+GLint LLGLSLShader::getAttribLocation(U32 attrib)
+{
+	if (attrib < mAttribute.size())
+	{
+		return mAttribute[attrib];
+	}
+	else
+	{
+		return -1;
+	}
+}
+
 void LLGLSLShader::uniform1i(const string& uniform, GLint v)
 {
 	GLint location = getUniformLocation(uniform);