[vte] build: Fix the build when an older vte VAPI is present on the system

[Christian Persch <chpe src gnome org>]

commit bc72a5fbc474c0c48527c461cba04e0253a6478c
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Fri Apr 15 18:09:41 2016 +0200

    build: Fix the build when an older vte VAPI is present on the system
    
    Pass --disable-since-check to valac on vala >= 0.31.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=762780

 configure.ac    |    3 +++
 src/Makefile.am |    4 ++++
 2 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 2a8d922..62f0187 100644
--- a/configure.ac
+++ b/configure.ac
@@ -368,12 +368,15 @@ AM_PROG_VALAC([0.18.0],[],[
 
 if test "$enable_test_application" = "yes"; then
   PKG_CHECK_MODULES([GTK_3_16],[gtk+-3.0 >= 3.16],[have_gtk_3_16=yes],[have_gtk_3_16=no])
+  AM_PROG_VALAC([0.31.1],[have_vala_0_31=yes],[have_vala_0_31=no])
 else
   have_gtk_3_16=no
+  have_vala_0_31=no
 fi
 
 AM_CONDITIONAL([ENABLE_TEST_APPLICATION],[test "$enable_test_application" = "yes"])
 AM_CONDITIONAL([HAVE_GTK_3_16],[test "$have_gtk_3_16" = "yes"])
+AM_CONDITIONAL([HAVE_VALA_0_31],[test "$have_vala_0_31" = "yes"])
 
 # ***************
 # Auxiliary tools
diff --git a/src/Makefile.am b/src/Makefile.am
index 8dcf170..3fd0f3a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -300,6 +300,10 @@ vte_ VTE_API_MAJOR_VERSION@_ VTE_API_MINOR_VERSION@_LDADD = \
        $(VTE_LIBS) \
        $(NULL)
 
+if HAVE_VALA_0_31
+vte_ VTE_API_MAJOR_VERSION@_ VTE_API_MINOR_VERSION@_VALAFLAGS += --disable-since-check
+endif
+
 if HAVE_GTK_3_16
 vte_ VTE_API_MAJOR_VERSION@_ VTE_API_MINOR_VERSION@_VALAFLAGS += -D GTK_3_16
 endif