[grilo] configure: Honour VAPIDIR environment variable

[SimÃn Pena <spenap src gnome org>]

commit 350d3a7c75472442313ddce160a059febb216f41
Author: Sam Thursfield <sam thursfield codethink co uk>
Date:   Wed Nov 23 19:03:40 2011 +0100

    configure: Honour VAPIDIR environment variable

 configure.ac |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 7d7b4c5..79fb71b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -201,7 +201,9 @@ if test "x$enable_vala" != "xno"; then
                         AC_MSG_ERROR([No Vala compiler found.])
                 fi
 
-                VAPIDIR=`$PKG_CONFIG --variable=vapidir $valapkg`
+                if test "x$VAPIDIR" = "x"; then
+                        VAPIDIR=`$PKG_CONFIG --variable=vapidir $valapkg`
+                fi
                 AC_SUBST([VAPIDIR])
 
                 AC_PATH_PROG([VALA_GEN_INTROSPECT], [vala-gen-introspect])