[vala] tests: Fix make distcheck

[Rico Tzschichholz <ricotz src gnome org>]

commit 03b481e5a3a837fb9844dc256fe1b011d93a1bcb
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Tue Jan 7 14:53:08 2020 +0100

    tests: Fix make distcheck

 tests/fastvapi/Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tests/fastvapi/Makefile.am b/tests/fastvapi/Makefile.am
index 86614655c..83f714663 100644
--- a/tests/fastvapi/Makefile.am
+++ b/tests/fastvapi/Makefile.am
@@ -14,7 +14,7 @@ check-fastvapi: $(top_builddir)/compiler/valac
                --disable-version-header \
                --vapidir $(top_srcdir)/vapi \
                --use-fast-vapi fastvapitest.vapi \
-               --basedir $(srcdir) \
+               --basedir $(builddir) \
                $(srcdir)/usefastvapitest.vala || exit 1; \
        rm -f fastvapitest.vapi fastvapitest.c usefastvapitest.c