Remove deprecated libcrypt, gets replaced by libxcrypt
    Add applicable Requires on libxcrypt
    
    Back in June, Björn Esser proposed to add OpenBSD-compatible bcrypt
    support to our implementation of crypt(3), and Zack Weinberg replied
    that it might actually make more sense to _remove_ libcrypt from
    glibc, freeing up libcrypt.so.1 and crypt.h to be provided by a
    separate project that could move faster.  (For instance, libxcrypt:
    https://github.com/besser82/libxcrypt)
    
    This commit is the glibc part of:
    https://fedoraproject.org/wiki/Changes/Replace_glibc_libcrypt_with_libxcrypt