check-keys and --disable-afs-string-to-key

[bjsa]

test/kdc/check-keys fails if heimdal is configured with --disable-afs-string-to-key.
quick workaround:

--- check-keys.in.orig	2017-01-03 16:18:36.427903622 +0100
+++ check-keys.in	2017-01-03 16:21:46.874400851 +0100
@@ -91,6 +91,8 @@
 	${sedvars} < ${CIN} > ${COUT}
 ${kadmin} cpw -p foo ${principal} || exit 1
 
+if ( grep -q "define ENABLE_AFS_STRING_TO_KEY" $top_builddir/include/config.h ) ; then
+
 sed -e 's/@keys@/des-cbc-crc:afs3-salt:test.h5l.se/' \
 	${sedvars} < ${CIN} > ${COUT}
 ${kadmin} cpw -p foo ${principal} || exit 1
@@ -99,4 +101,6 @@
 	${sedvars} < ${CIN} > ${COUT}
 ${kadmin} cpw -p foo ${principal} || exit 1
 
+fi
+
 exit 0