fix segfaulting when managing exceptions

we were loading gtk+2 in order to set my_gtk_main_level to
gtk_main_level
which resulted in us strange segfaults when eg trying to save a package:

$ gdb -q --args perl ./gurpmi ./coreutils-doc-8.23-1.mga5.noarch.rpm
(gdb) s
generic_exceptions_handler () at GClosure.xs:774
774          if ((*my_gtk_main_level)())
(gdb) print my_gtk_main_level
$1 = (guint (*)()) 0x7fffe75eebf0
(gdb) print *my_gtk_main_level
Cannot access memory at address 0x7fffe75eebf0
(gdb) s

Program received signal SIGSEGV, Segmentation fault.
0x00007fffe75eebf0 in ?? ()

(gdb) print gtk_main_level
$2 = {guint (void)} 0x7fffee90d650 <gtk_main_level>

0 files changed, 0 insertions, 0 deletions