Allow drawing sun in OpenGL1 renderer

Removed #if 0 ... #endif around RB_DrawSun().
Merged improvements and changes from OpenGL2 renderer.

code/renderergl1/tr_local.h

@@ -1326,7 +1326,7 @@ SKIES
 void R_BuildCloudData( shaderCommands_t *shader );
 void R_InitSkyTexCoords( float cloudLayerHeight );
 void R_DrawSkyBox( shaderCommands_t *shader );
-void RB_DrawSun( void );
+void RB_DrawSun( float scale, shader_t *shader );
 void RB_ClipSkyPolygons( shaderCommands_t *shader );
 
 /*