SHA224Update in libc and libmd. Solaris uses "void *" where we use
"unsigned char *" so we need a check for that too. Solaris sha2.h
defines SHA224, SHA256, SHA384, and SHA512 so rename those tokens.
Adapted from changes from Vladimir Marek in bug #641.
Currently supports SHA-224, SHA-256, SHA-384, SHA-512.
TODO: checksum format validation in parser and base64 support.
checksum support for ldap sudoers