[gupnp] Don't error out if vapigen cannot be found

[Jens Georg <jensgeorg src gnome org>]

commit 3d1cbab2314d4fe849618369df3e754bb1d6470f
Author: Jens Georg <mail jensge org>
Date:   Wed Oct 24 20:21:06 2012 +0200

    Don't error out if vapigen cannot be found

 m4/vapigen.m4 |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/m4/vapigen.m4 b/m4/vapigen.m4
index d8c86f6..df6395d 100644
--- a/m4/vapigen.m4
+++ b/m4/vapigen.m4
@@ -37,5 +37,5 @@ AC_DEFUN([VALA_PROG_VAPIGEN],
            [AC_MSG_RESULT([yes])],
            [AC_MSG_RESULT([yes])],
            [AC_MSG_RESULT([no])
-            AC_MSG_ERROR([Vala API Generator $1 not found.])])])])
+            AC_MSG_WARN([Vala API Generator $1 not found.])])])])
 ])