[libsoup] Improve vala vs g-i error reporting situation

[Dan Winship <danw src gnome org>]

commit c1cbf4dbbd2d36948e093a88305b04f31f26e878
Author: Dan Winship <danw gnome org>
Date:   Mon Apr 25 11:36:08 2016 -0400

    Improve vala vs g-i error reporting situation
    
    VAPIGEN_CHECK() will error out if --disable-introspection is passed
    and --disable-vala is not, so make --disable-introspection imply
    --disable-vala (unless --enable-vala was explicitly passed).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=764090
    (fallout from https://bugzilla.gnome.org/show_bug.cgi?id=755389)

 configure.ac |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 3f42770..c802472 100644
--- a/configure.ac
+++ b/configure.ac
@@ -167,6 +167,9 @@ dnl *** gobject-introspection ***
 dnl *****************************
 GOBJECT_INTROSPECTION_CHECK([0.9.5])
 
+if test "$found_introspection" != "yes" -a "$enable_vala" = ""; then
+       enable_vala=no
+fi
 VAPIGEN_CHECK()
 
 AC_MSG_CHECKING([for glib-networking (glib TLS implementation)])