added non-standard datum name lookup

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@42680 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/proj/convert.c

@@ -750,6 +750,8 @@ static const char *papszDatumEquiv[] = {
     "Militar_Geographische_Institut",
     "Potsdam_Datum_83",
     "Deutsches_Hauptdreiecksnetz",
+    "South_American_1969",
+    "South_American_Datum_1969",
     NULL
 };