They were on SLES11 Disk 1. Crazy me, I thought the C compiler would
be on the SDK disk.
I also thought that Yast indexed all packages on the local disk so once
a Repository was read (e.g. SLES 11 Disk 1) that it would know where to
find all the packages on it.
This is a serious flaw, because it means that all disks have to be
available (online) when doing a search in order for a package to be
found.