Ok... even libc6 and libc-bin from marmistrz do not cause a problem. CSSU time (this might take a while with this connection though)

EDIT: haha... spoke too soon. Internal error: Application 'Calendar' closed all over the place now. Thought it was suspicious Aapo mentioned uninstalling calendar. Not good. Though for email it was lack of ARM errata, maybe this needs to be taken into account when compiling libc

EDIT2: Uninstalled libc-bin (this is useless it seems), reinstalled libc6 from sdk repo and calendar, back to normal... almost. First of all, installing marmistrz's libc6(or -bin, not sure as did both) tried removing /sys in postinst... :/ After reinstall it cries lack of ldconfig. Guess it's time for another flash. GCC/++ so far no issues (assuming missing includes were from bad prog, will give it another try with something lighter)