rtorrent: fix deps
gcc473: fix libgcc_eh link sequence

due to a bug in the gcc specs, adding -lgcc_eh can result in omission
of -lgcc, so the symbols dont get pulled in.

closes #232

the specs bug is according to dalias
gcc/config/gnu-user.h
 #undef LINK_GCC_C_SEQUENCE_SPEC
 #define LINK_GCC_C_SEQUENCE_SPEC \
- "%{static:--start-group} %G %L %{static:--end-group}%{!static:%G}"
+ "--start-group %G %{static:%L} --end-group"
gcc474: fix libgcc_eh link sequence

see parent's commits message.