[gnome-sound-recorder] configure: Drop id3mux check failure to a warning

[Margaret Ford <megford src gnome org>]

commit 3de385540bdce2d22114a9b9fe0693a69bd05e94
Author: David King <amigadave amigadave com>
Date:   Tue Mar 21 07:15:11 2017 +0000

    configure: Drop id3mux check failure to a warning
    
    The comment above the check states that it should not indicate a
    failure, so use AC_MSG_WARN instead of AC_MSG_ERROR.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=780340
    
    Signed-off-by: Meg Ford <megford gnome org>

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f852dd1..1174d1a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -100,7 +100,7 @@ do
                AC_MSG_RESULT([yes])
        else
                AC_MSG_RESULT([no])
-               AC_MSG_ERROR([
+               AC_MSG_WARN([
                        Cannot find required GStreamer-1.0 plugin '$1'.
                        It should be part of gst-plugins-bad. Please install it.
                ])