SDK: Enforce GDK_NATIVE_WINDOWS=true for linux scripts

SDK BUG 2232091

Change-Id: I2a000054545b7865769054d1fdc733e50f06edd5

tools/sdkmanager/app/etc/android

@@ -71,6 +71,10 @@ else
     os_opts=
 fi
 
+if [ `uname` = "Linux" ]; then
+    export GDK_NATIVE_WINDOWS=true
+fi
+
 if [ "$OSTYPE" = "cygwin" ] ; then
     jarpath=`cygpath -w  "$frameworkdir/$jarfile"`
     progdir=`cygpath -w  "$progdir"`