ref_gl: disable VBO. Rename r_vbo to gl_vbo to ignore existing config values as it was enabled by default

ref_gl/gl_opengl.c

@@ -901,12 +901,8 @@ static void R_CheckVBO( void )
 		def = "0";
 	}
 
-	r_vbo = gEngfuncs.Cvar_Get( "r_vbo", def, flags, "draw world using VBO" );
+	r_vbo = gEngfuncs.Cvar_Get( "gl_vbo", def, flags, "draw world using VBO (known to be glitchy)" );
-	r_vbo_dlightmode = gEngfuncs.Cvar_Get( "r_vbo_dlightmode", dlightmode, FCVAR_ARCHIVE, "vbo dlight rendering mode(0-1)" );
+	r_vbo_dlightmode = gEngfuncs.Cvar_Get( "gl_vbo_dlightmode", dlightmode, FCVAR_ARCHIVE, "vbo dlight rendering mode(0-1)" );
-
-	// check if enabled manually
-	if( CVAR_TO_BOOL(r_vbo) )
-		r_vbo->flags |= FCVAR_ARCHIVE;
 }
 
 /*

ref_gl/gl_rsurf.c

@@ -1794,7 +1794,7 @@ void R_GenerateVBO( void )
 	// we do not want to write vbo code that does not use multitexture
 	if( !GL_Support( GL_ARB_VERTEX_BUFFER_OBJECT_EXT ) || !GL_Support( GL_ARB_MULTITEXTURE ) || glConfig.max_texture_units < 2 )
 	{
-		gEngfuncs.Cvar_FullSet( "r_vbo", "0", FCVAR_READ_ONLY );
+		gEngfuncs.Cvar_FullSet( "gl_vbo", "0", FCVAR_READ_ONLY );
 		return;
 	}