* Sanity-check the results of krb5-config before proceeding.
* Fall back on manual probing if krb5-config results don't work.
* Add --with-krb5-include and --with-krb5-lib configure options.
* Add --with-remctl-include and --with-remctl-lib configure options.
* Add --with-gssapi-include and --with-gssapi-lib configure options.
* Don't break if the user clobbers CPPFLAGS at build time.
* Suppress error output from krb5-config probes.
* Prefer KRB5_CONFIG over a path constructed from --with-*.
* Update GSS-API probes for Solaris 10's native implementation.
* Change AC_TRY_* to AC_*_IFELSE as recommended by Autoconf.

Also strip out more outdated AFS kaserver instructions from README.