libdpkg: Fix comment header titles

lib/dpkg/pkg-db.c

@@ -1,6 +1,6 @@
 /*
  * libdpkg - Debian packaging suite library routines
- * pkg-db.c - Low level package database routines (hash tables, etc.)
+ * pkg-db.c - low level package database routines (hash tables, etc.)
  *
  * Copyright © 1995 Ian Jackson <ian@chiark.greenend.org.uk>
  * Copyright © 2008-2012 Guillem Jover <guillem@debian.org>

lib/dpkg/utils.c

@@ -1,6 +1,6 @@
 /*
  * libdpkg - Debian packaging suite library routines
- * utils.c - Helper functions for dpkg
+ * utils.c - helper functions for dpkg
  *
  * Copyright © 2001 Wichert Akkerman <wakkerma@debian.org>
  *

lib/dpkg/version.c

@@ -1,6 +1,6 @@
 /*
  * libdpkg - Debian packaging suite library routines
- * version.c - Version handling functions
+ * version.c - version handling functions
  *
  * Copyright © 1995 Ian Jackson <ian@chiark.greenend.org.uk>
  *