[PATCH] automake: avoid harmful directory change before invoking valac

The current am__cd right before invoking valac invalidates
any relative flags setup done before that.

https://bugzilla.gnome.org/show_bug.cgi?id=740825
---
 bin/automake.in | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/bin/automake.in b/bin/automake.in
index 4cee0d0..3082207 100644
--- a/bin/automake.in
+++ b/bin/automake.in
@@ -5476,6 +5476,7 @@ sub lang_vala_finish_target
   my $silent = silent_flag ();
   my $stampfile = "\$(srcdir)/${derived}_vala.stamp";
 
+  map { !/^\// && ($_ = "\$(srcdir)\/" . $_) } @vala_sources;
   $output_rules .=
     "\$(srcdir)/${derived}_vala.stamp: @vala_sources\n".
 # Since the C files generated from the vala sources depend on the
@@ -5485,7 +5486,7 @@ sub lang_vala_finish_target
 # Thus we need to create the stamp file *before* invoking valac, and to
 # move it to its final location only after valac has been invoked.
     "\t${silent}rm -f \$\@ && echo stamp > \$\@-t\n".
-    "\t${verbose}\$(am__cd) \$(srcdir) && $compile @vala_sources\n".
+    "\t${verbose}$compile -d \$(srcdir) @vala_sources\n".
     "\t${silent}mv -f \$\@-t \$\@\n";
 
   push_dist_common ($stampfile);
-- 
2.2.0