Remove rte_hash_crc.h include from wr_pcap.h and add a delay to wait for packets to be sent

Signed-off-by: Keith Wiles <keith.wiles@windriver.com>
It consists of 3 commits: improvements to the pktgen-random.c unit tests, the real CentOS compilation fixes and a small update to tap.{c,h} so they are identical to those from zorgnax/libtap on github.

Signed-off-by: Keith Wiles <keith.wiles@windriver.com>