libpcap: fix noMMU build

Add a "uClinux is also Linux" patch to fix build for Blackfin.

Fixes:
http://autobuild.buildroot.net/results/e19/e19e8ebb46560050029576baa040f2c6928e6424/



Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>