This issue is fixed in recent grml-live version: we use linux-libc-dev for
GRML_FULL and linux-kernel-headers-grml for GRML_MEDIUM nowadays.
Closing this bugreport therefore.
The 64bit flavours of grml already use linux-libc-dev instead of linux-kernel-
headers-grml by default. The 32bit versions (grml/grml-medium) got linux-libc-
dev by manual installation, we should support that in a cleaner way through
grml-live.