Just in case anyone else hits these issues building on Ubuntu12.04.
I was building the full image for the p1010rds, but the bugs will be common to other platforms:
1 - gcc 4.7 fails to build the cross compiler. This is a known gcc regression.
See GCC Bugzilla 51969 and apply the simple patch to gengtype.c
2 - The tcpdump library fails to configure. This can occurr if the host build system has a pcap
configuration file (/usr/bin/pcap-config). The configure stage of build parses out the library
directory from this file and attempts to use it for linking, which then fails a bitbake sanity check.
The simple fix for this is to temporarily rename this file, although the actual bug is in the auto configuration