Cleaning up some testing stuff.

- The Makefiles now run btest with "-f diag.log" so that diangnostics
  output will always be written into that file.

- Makefiles now hardcode path to btest to avoid picking up the wrong version
  if in PATH.

- The canonifier scripts now live in testing/scripts, and they are
  used from both btest/ and external/.

- There's a new diff-remove-uids scripts that removed connection UIDs
  for diffing. The external/* tests now use that by default.

- Timestamp removal now has its own script: diff-remove-timestamps.
  diff-canonifier calls that.

- All Makefile have a "brief" target that runs btest with -b.

- The higher-level directories have Makefile to call the subdirs.

testing/scripts/diff-remove-uids

@@ -0,0 +1,21 @@
+#! /usr/bin/awk -f
+#
+# A diff canonifier that removes all connection UIDs.
+
+BEGIN { IFS="\t"; OFS="\t"; }
+
+column > 0 {
+    $column = "XXXXXXXXXXX";
+    }
+
+/^#/ {
+    for ( i = 0; i < NF; ++i ) {
+        if ( $i == "uid" )
+            column = i - 1;
+        }
+    }
+
+{ print }
+
+
+