tools: fix the PowerPC build

On ppc archtecture the "nm_bt_vtable_network_server" symbol in the small
objects section instead of .bss, represencted by a "S" letter. Also
include "G" which is an equivalent thing for initialized data. We don't
seem to have such objects at the moment, but when we do it could result
in a nasty surprise.

tools/create-exports-NetworkManager.sh

@@ -36,7 +36,7 @@ call_nm() {
 
 get_symbols_nm () {
     call_nm ./src/.libs/libNetworkManager.a |
-        sed -n 's/^[tTDRB] //p' |
+        sed -n 's/^[tTDGRBS] //p' |
         _sort
 }