[14:47-0]:/home/xxx/seastar→master* > g++ -print-search-dirs
[....]
libraries: =/usr/lib/gcc/x86_64-linux-gnu/6/:[....]
[14:47-0] :/home/xxx/seastar→master* > locate libgcc_s
/lib/i386-linux-gnu/libgcc_s.so.1
/lib/x86_64-linux-gnu/libgcc_s.so.1
/usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/5/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/6/libgcc_s.so
/usr/lib/gcc/x86_64-linux-gnu/6/libgcc_s.so.1
/usr/lib32/libgcc_s.so.1
[14:47-0] :/home/xxx/seastar→master* > g++  -O0 -g -Wl,--no-as-needed -fvisibility=hidden -pthread -laio -lboost_program_options -lboost_system -lboost_filesystem  -lm -lboost_thread -lcryptopp -lrt -lgnutls -lgnutlsxx -llz4 -lprotobuf -ldl -lgcc_s -lunwind -lxenstore -static-libgcc -static-libstdc++ -Wl,--whole-archive -Wl,--no-whole-archive -lrt -lm -ldl -lhwloc -lnuma -lpciaccess -lxml2 -lz -lcares-seastar
[works fine!]

[14:47-0] :/home/xxx/seastar→master* > g++  -O0 -g -Wl,--no-as-needed -fvisibility=hidden -pthread -laio -lboost_program_options -lboost_system -lboost_filesystem  -lm -lboost_thread -lcryptopp -lrt -lgnutls -lgnutlsxx -llz4 -lprotobuf -ldl -lgcc_s -lunwind -lxenstore -static-libgcc -static-libstdc++ -Wl,--whole-archive -Wl,--no-whole-archive -lrt -lm -ldl -lhwloc -lnuma -lpciaccess -lxml2 -lz -lcares-seastar -static
/usr/bin/ld: cannot find -lgcc_s
[...]
collect2: error: ld returned 1 exit status