gnu: ntp: Update to 4.2.8p7 [security fixes].

This fixes CVE-2015-7704 and CVE-2016-{1547,1548,1549,1551,2516,2517,
2518,2519}.

* gnu/packages/ntp.scm (ntp): Update to 4.2.8.p7.

gnu/packages/ntp.scm

@@ -38,7 +38,7 @@ (define-module (gnu packages ntp)
 (define-public ntp
   (package
    (name "ntp")
-   (version "4.2.8p6")
+   (version "4.2.8p7")
    (source (origin
 	    (method url-fetch)
 	    (uri (string-append
@@ -47,7 +47,7 @@ (define-public ntp
                   "/ntp-" version ".tar.gz"))
 	    (sha256
 	     (base32
-              "0j509gd0snj8dq15rhfv2v4wisfaabya1gmgqslk1kisawf0wgaq"))
+              "1p100856h17nb0kpnppy70nja57hbcc95h7shhxvw6mhl030rll1"))
             (modules '((guix build utils)))
             (snippet
              '(begin