Remove custom lock types in favor of native C++11 mutexes

No longer using RAII wrappers around pthread_mutex_t and pthread_cond_t
in favor of the C++11 std::mutex, std::recursive_mutex, and
std::condition_variable data types.

src/fish.cpp

@@ -378,7 +378,6 @@ int main(int argc, char **argv) {
     proc_init();
     event_init();
     builtin_init();
-    function_init();
     misc_init();
     reader_init();
     history_init();