[gssdp] Don't error out if vapigen isn't found

[Jens Georg <jensgeorg src gnome org>]

commit ab591c3cc3750decaec8923eb99677b7bb6852be
Author: Jens Georg <mail jensge org>
Date:   Sun Oct 14 16:33:10 2012 +0200

    Don't error out if vapigen isn't found
    
    https://bugzilla.gnome.org/show_bug.cgi?id=686039

 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.])])])])
 ])