profiles: drop USE=cracklib from base/make.defaults.

profiles: drop USE=cracklib from base/make.defaults.

The "cracklib" USE flag has long (since 2007ish) been enabled by
default for all profiles. But, the features that it provides are not
critical for any of the packages that use it: typically, the library
is used to evaluate a candidate password and to prevent the user from
choosing a weak one.

Since the flag is not critical, and because we now have per-package
USE defaults, this commit removes it from base/make.defaults.

Closes: https://bugs.gentoo.org/635698