[vte] build: Fix compilation of unittests

[Egmont Koblinger <egmontkob src gnome org>]

commit a31a41d2a93ef45c3940d714f82f58c6b3f9d7d8
Author: Egmont Koblinger <egmont gmail com>
Date:   Thu Mar 16 22:07:40 2017 +0100

    build: Fix compilation of unittests
    
    https://bugzilla.gnome.org/show_bug.cgi?id=780146

 src/vteconv.cc  |    2 +-
 src/vtetypes.cc |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/vteconv.cc b/src/vteconv.cc
index b78d392..3cd159e 100644
--- a/src/vteconv.cc
+++ b/src/vteconv.cc
@@ -771,7 +771,7 @@ int
 main (int argc,
       char *argv[])
 {
-        g_test_init (&argc, &argv, NULL);
+        g_test_init (&argc, &argv, nullptr);
 
         g_test_add_func ("/vte/conv/utf8/strlen", test_utf8_strlen);
         g_test_add_func ("/vte/conv/utf8/validate", test_utf8_validate);
diff --git a/src/vtetypes.cc b/src/vtetypes.cc
index 1365a29..119c3b5 100644
--- a/src/vtetypes.cc
+++ b/src/vtetypes.cc
@@ -407,7 +407,7 @@ test_util_smart_fd(void)
 int
 main(int argc, char *argv[])
 {
-        g_test_init (&argc, &argv, NULL);
+        g_test_init (&argc, &argv, nullptr);
 
         g_test_add_func("/vte/c++/grid/coords", test_grid_coords);
         g_test_add_func("/vte/c++/grid/span", test_grid_span);