OpenGL2: Render dlights only when r_lightmap is 0.

https://github.com/ioquake/ioq3/issues/246

code/renderergl2/tr_shade.c

@@ -1598,7 +1598,7 @@ void RB_StageIteratorGeneric( void )
 	// 
 	// now do any dynamic lighting needed
 	//
-	if ( tess.dlightBits && tess.shader->sort <= SS_OPAQUE
+	if ( tess.dlightBits && tess.shader->sort <= SS_OPAQUE && r_lightmap->integer == 0
 		&& !(tess.shader->surfaceFlags & (SURF_NODLIGHT | SURF_SKY) ) ) {
 		if (tess.shader->numUnfoggedPasses == 1 && tess.xstages[0]->glslShaderGroup == tr.lightallShader
 			&& (tess.xstages[0]->glslShaderIndex & LIGHTDEF_LIGHTTYPE_MASK) && r_dlightMode->integer)