Tries to lock lock for reading. If lock is already locked for
writing by another thread or if another thread is already waiting to
lock lock for writing, immediately returns FALSE. Otherwise locks
lock for reading and returns TRUE. This lock has to be unlocked by
g_static_rw_lock_reader_unlock().
Tries to lock lock for reading. If lock is already locked for writing by another thread or if another thread is already waiting to lock lock for writing, immediately returns FALSE. Otherwise locks lock for reading and returns TRUE. This lock has to be unlocked by g_static_rw_lock_reader_unlock().