Make minimap size 1.8 higher

This factor has been chosen because :
1) It allows the toplist to be able to still display 10 karts (maximum number reached in story mode or in networking (currently 12 but will be 8-10 for release according to Benau))
2) This size should fit nicely in the android GUI.

Otherwise, there is still some margin before it hinders view in 4:3 resolutions.

src/states_screens/race_gui.cpp

@@ -84,7 +84,7 @@ RaceGUI::RaceGUI()
 
     // Originally m_map_height was 100, and we take 480 as minimum res
     float scaling = irr_driver->getFrameSize().Height / 480.0f;
-    const float map_size = 100.0f;
+    const float map_size = 180.0f;
     const float top_margin = 3.5f * m_font_height;
     
     if (UserConfigParams::m_multitouch_enabled &&