[gtksourceview] Fix make distcheck

[Sébastien Wilmet <swilmet src gnome org>]

commit 00d8371d4bb6953f44a3712cf28cb115e8e03a82
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Dec 16 13:17:00 2013 +0100

    Fix make distcheck
    
    When build dir != src dir

 tests/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 09d99aa..8d0a4e6 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -158,7 +158,7 @@ python_tests =                      \
        test-completion.py      \
        test-widget.py
 
-TESTS_ENVIRONMENT = G_TEST_SRCDDIR="$(top_srcdir)/tests"
+TESTS_ENVIRONMENT = G_TEST_SRCDIR="$(abs_srcdir)"
 TESTS = $(UNIT_TEST_PROGS)
 
 EXTRA_DIST =                           \