[libvirt] [libvirt-glib] Make vala optional by default

[Christophe Fergeau]

04368c60c added vala binding generation to libvirt-glib. To do
that, it needs vapigen, so it checks for its presence during
configure.
However, configure errors out when vapigen is not found
unless --disable-vala has been explicitly passed. In particular,
vapigen must be available when running autogen.sh/configure without
arguments.

This commit changes this behaviour to disable building of vala
bindings when vapigen can't be found and no arguments were
passed to configure. It will still error out when --enable-vala was
specified and vapigen is not available.
---
 configure.ac |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index c474f0b..b3fa808 100644
--- a/configure.ac
+++ b/configure.ac
@@ -205,12 +205,13 @@ if test "x$enable_introspection" = "xyes" ; then
         if test "x$enable_vala" != "xno" ; then
                 AC_PATH_PROG(VAPIGEN, vapigen, no)
                 if test "x$VAPIGEN" != "xno"; then
-                        if test "x$enable_vala" == "xcheck" ; then
-                                enable_vala=yes
-                                AC_SUBST(VAPIGEN)
-                        fi
+                        enable_vala=yes
                 else
-                        AC_MSG_ERROR([Cannot find the "vapigen" binary in your PATH])
+                        if test "x$enable_vala" != "xcheck" ; then
+                                AC_MSG_ERROR([Cannot find the "vapigen" binary in your PATH])
+                        else
+                                enable_vala=no
+                        fi
                 fi
         fi
 fi
-- 
1.7.6.4