fast pstack + uniqstack for linux, use libunwind.
for static linking, clone https://github.com/libunwind/libunwind, and build from source.
However, to avoid repeatedly read proc maps in multi-thread process, used a hack init_global_proc_map from
https://github.com/fantasyzh/libunwind fork repo.
libunwind_path=/usr/local
g++ -o uniqstack --std=gnu++11 -g uniqstack.cpp -pthread -I$libunwind_path/include/ -L$libunwind_path/lib/ -Wl,-Bstatic -lunwind-ptrace -lunwind-x86_64 -lunwind -Wl,-Bdynamic