to make-time substitution.
e.g. FOO=@bar@/stuff --> FOO=${bar}/stuff
This makes it more clear where the various configuration directives
are coming from.
LCRYPT = @CRYPTLIB@
LIBS = @LIBS@
-LOGDIR = @logdir@
-RADDBDIR = @raddbdir@
-RUNDIR = @localstatedir@/run
-SBINDIR = @sbindir@
-RADIR = @radacctdir@
+LOGDIR = ${logdir}
+RADDBDIR = ${raddbdir}
+RUNDIR = ${localstatedir}/run
+SBINDIR = ${sbindir}
+RADIR = ${radacctdir}
LIBLTDL = @LIBLTDL@
INCLTDL = @INCLTDL@