package/libtorrent-rasterbar: fix build on m68k_cf

An internal compiler error is raised on m68k_cf at dwarf2cfi.c:2802 in
connect_traces. Error can be fixed by adding -fno-defer-pop, see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58864

Fixes:
 - http://autobuild.buildroot.org/results/746f60fadb40288341c1e5642cfcf6373b70583a



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>