Revert "Merge pull request #615 from pinwing/dhcp6c"

This reverts commit fcee70282e3f3041def62d4e63b5d4995d1d9bea, reversing
changes made to 3f8a9a3f5b85bc0ebbfd62dd646b496a9c1ae2a4.

Conflicts:
	release/src/router/rc/udhcpc.c
Merge pull request #652 from pinwing/dhcp6c

Revert "Merge pull request #615 from pinwing/dhcp6c"