Use PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP in dlfcn.c

Needed by certain android bsp.

This is basically a cherry-pick from android upstream. The original code
is available as part of the bionic commit e19d702.

Change-Id: I090fbc06fc9453a3419eb9ec05b0cd932d17c971
Signed-off-by: Yuan-Chen Cheng <yc.cheng@canonical.com>
Signed-off-by: Ricardo Salveti de Araujo <rsalveti@rsalveti.net>