Use autoreconf, not autoconf&&automake&&etc in autogen.sh

The autoreconf tool deals much better with detecting which tools to
use on your particular platform, handling cases where your
install-sh script gets stable, and lots of other little tricky
issues.

We still fall back to autoconf&&automake&&etc in the case where
"`which autoreconf 2>/dev/null`" says something we can't run.

This is the first change of the 0.2.3.x series.

autogen.sh

@@ -1,5 +1,9 @@
 #!/bin/sh
 
+if [ -x "`which autoreconf 2>/dev/null`" ] ; then
+  exec autoreconf -ivf
+fi
+
 set -e
 
 # Run this to generate all the initial makefiles, etc.

changes/autoreconf

@@ -0,0 +1,5 @@
+  o Minor build changes:
+    - Use autoreconf to launch autoconf, automake, etc from autogen.sh.
+      This is more robust against some of the failure modes associated
+      with running the autotools chain on its own.
+