Commits 1e4bdcfe and 8df1965d introduced a regression

I see the following on HP-UX:

    $ ./configure --prefix=$HOME/krb5-1.12.1 --with-readline
    ./configure[2587]: ==: A test command parameter is not valid.
    ./configure[2594]: ==: A test command parameter is not valid.
    checking for gcc... no
    checking for cc... cc

and

    $ make install
    mkdir /krb5kdc
    mkdir: Kein Zugriff möglich auf /: Berechtigung verweigert
    *** Fehlerrückkehrcode 2
   
    Stopp.

This little patch makes it work as expected.