odhcploc: new package

Adds odhcploc, a network utility to scan for (rogue) DHCP servers.

[Thomas:
- remove ODHCPLOC_SOURCE line, not needed since the value was the
  default
- use 'make install' instead of manually installing the program
- use TARGET_CONFIGURE_OPTS instead of passing just CC and LD
- use tab for indentation inside command definitions instead of spaces]

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>