[vte] spawn: Use nullptr not NULL

[Christian Persch <chpe src gnome org>]

commit b1591c62a5018350c7c561bb91ce3733be21b176
Author: Christian Persch <chpe src gnome org>
Date:   Fri May 1 20:03:42 2020 +0200

    spawn: Use nullptr not NULL

 src/vtepty.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/vtepty.cc b/src/vtepty.cc
index 94708b95..1f79a0d0 100644
--- a/src/vtepty.cc
+++ b/src/vtepty.cc
@@ -655,7 +655,7 @@ _vte_pty_check_envv(char const* const* strv)
   for (int i = 0; strv[i]; ++i) {
           const char *str = strv[i];
           const char *equal = strchr(str, '=');
-          if (equal == NULL || equal == str)
+          if (equal == nullptr || equal == str)
                   return false;
   }