build: support for "development build"

* configure.ac

    Add the --enable-dev-build flag. It controls the DEV_BUILD
    define for autoconf and automake, which can be used to
    conditionally build in code that is only intended for development..

Signed-off-by: Avneesh Sachdev <avneesh@sproute.com>
diff --git a/configure.ac b/configure.ac
index 3818990..f027762 100755
--- a/configure.ac
+++ b/configure.ac
@@ -306,6 +306,9 @@
 AC_ARG_ENABLE([protobuf],
   AS_HELP_STRING([--enable-protobuf], [Enable experimental protobuf support]))
 
+AC_ARG_ENABLE([dev_build],
+    AS_HELP_STRING([--enable-dev-build], [build for development]))
+
 if test x"${enable_gcc_rdynamic}" != x"no" ; then
   if test x"${enable_gcc_rdynamic}" = x"yes" -o x"$COMPILER" = x"GCC"; then
     LDFLAGS="${LDFLAGS} -rdynamic"
@@ -324,6 +327,11 @@
    AC_DEFINE(HAVE_FPM,,Forwarding Plane Manager support)
 fi
 
+if test "x${enable_dev_build}" = "xyes"; then
+   AC_DEFINE(DEV_BUILD,,Build for development)
+fi
+AM_CONDITIONAL([DEV_BUILD], [test "x$enable_dev_build" = "xyes"])
+
 #
 # Logic for protobuf support.
 #