auto_test/crypto_test.c:
- test "endtoend": increased timeout from default ~5s to 15s, making it pass on slower systems
- signed/unsiged warning fixed by cast
While doing the checks configure might generate "core" files and will
then try to remove them. Having a "core" directory generates an error
while runing the configure script.
There's no workaround but to rename the core directory.
