safeclib: new package

safec fork with all C11 Annex K functions

This library implements the secure C11 Annex K functions on
top of most libc implementations, which are missing from them.

https://rurban.github.io/safeclib/



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>