Log Message:
Import dhcpcd-7.0.1 with the following changes:
*  hooks: remove use of local builtin for better portability
*  Fix build issue when `__GNUC__ <= 2` (thanks to Chris Hathhorn)
*  dhcpcd: don't log errors working out carrier for departed interfaces
*  ipv4: allow configuration of static broadcast address
*  if: don't set MTU during interface discovery
*  if: don't activate non matching interfaces to commandline ones
*  configure: make `--includedir=/usr/src/foo` work
*  eloop-bench: fix hangs when using a large number of cycles
*  dhcp: don't bind when we've just probed an address to inform