libnfc 1.7.0-rc6

Update libnfc to latest, add config file (generated by brew, in prefix)
and add a patch to support PN532-based NFC devices with USB CDC/ACM
interfaces, such as the OpenPCD2

http://www.openbeacon.org/OpenPCD_2_RFID_Reader_for_13.56MHz

Closes #18272.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>