samba4: security bump to version 4.7.6

CVE-2018-1050: Vulnerability to a denial of service attack when the RPC
spoolss service is configured to be run as an external daemon.

https://www.samba.org/samba/security/CVE-2018-1050.html

CVE-2018-1057: Authenticated users might change any other users'
passwords, including administrative users and privileged service
accounts (eg Domain Controllers).

https://www.samba.org/samba/security/CVE-2018-1057.html

Add clnt_create() test result to cache to fix cross configure breakage.

Cc: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/samba4/samba4-cache.txt

@@ -38,3 +38,4 @@ Checking value of _NSIG: "65"
 Checking value of SIGRTMAX: "64"
 Checking value of SIGRTMIN: "34"
 Checking errno of iconv for illegal multibyte sequence: "0"
+checking for clnt_create(): OK

package/samba4/samba4.hash

@@ -1,3 +1,4 @@
-# Locally calculated
-sha256 fb12d0c4452f85b67b78bbeabd4c762d8feb8ff83e39d044d285120c2c488247  samba-4.7.4.tar.gz
+# Locally calculated after checking pgp signature
+# https://download.samba.org/pub/samba/stable/samba-4.7.6.tar.asc
+sha256 1eede30fc8ef6504e24602fb72b00baa0a7b73b59f16d25cb0771dc8c7c57d6e  samba-4.7.6.tar.gz
 sha256 8ceb4b9ee5adedde47b31e975c1d90c73ad27b6b165a1dcd80c7c545eb65b903  COPYING

package/samba4/samba4.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-SAMBA4_VERSION = 4.7.4
+SAMBA4_VERSION = 4.7.6
 SAMBA4_SITE = https://download.samba.org/pub/samba/stable
 SAMBA4_SOURCE = samba-$(SAMBA4_VERSION).tar.gz
 SAMBA4_INSTALL_STAGING = YES