Add a simple (to be expanded) library of functions for the regression tests,

to handle the ones which output to stdout and have output in regress.$test.out,
etc.  More freeform macros should and will be written, but these are the most
prominent and most straightforward sort of tests we have around, so it makes
sense to try to accomodate them.

tools/regression/usr.bin/regress.m4

@@ -0,0 +1,23 @@
+# $FreeBSD$
+
+define(`REGRESSION_START',
+TESTDIR=$1
+if [ -z "$TESTDIR" ]; then
+  TESTDIR=.
+fi
+cd $TESTDIR
+
+STATUS=0)
+
+define(`REGRESSION_TEST',
+echo "Running test $1"
+$2 | diff -u regress.$1.out -
+if [ $? -eq 0 ]; then
+  echo "PASS: Test $1 detected no regression."
+else
+  STATUS=$?
+  echo "FAIL: Test $1 failed: regression detected.  See above."
+fi)
+
+define(`REGRESSION_END',
+exit $STATUS)