keep filename findable/non-generic (used for LSB e.g. /usr/share/icons/hicolor/)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@50243 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/icons/grass.desktop

@@ -5,5 +5,5 @@ Name=GRASS GIS
 Comment=Geographic Information System
 Categories=Education;Science;Geoscience;Geography;
 Exec=grass7
-Icon=/usr/share/icons/grass.png
+Icon=/usr/share/icons/grass-48x48.png
 Terminal=true