gis/OWSLib: Add Python 3 support.

Signed-off-by: Benjamin Trigona-Harany <bosth@alumni.sfu.ca>

gis/OWSLib/OWSLib.SlackBuild

@@ -70,6 +70,9 @@ find -L . \
  -o -perm 440 -o -perm 400 \) -exec chmod 644 {} \;
 
 python setup.py install --root=$PKG
+if $(python3 -c 'import sys' 2>/dev/null); then
+  python3 setup.py install --root=$PKG
+fi
 
 find $PKG | xargs file | grep -e "executable" -e "shared object" | grep ELF \
   | cut -f 1 -d : | xargs strip --strip-unneeded 2> /dev/null || true