*: make GNU licensing statement forms more regular

This change retains "or later" state! No licensing _changes_ here,
only form is adjusted (article, space between "GPL" and "v2" and so on).

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/procps/sysctl.c b/procps/sysctl.c
index fc601d6..20b372c 100644
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -4,7 +4,7 @@
  *
  * Copyright 1999 George Staikos
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  *
  * Changelog:
  * v1.01   - added -p <preload> to preload values from a file