package/samba4: bump version to 4.15.6

Release notes: https://www.samba.org/samba/history/samba-4.15.6.html

Added new answer to samba4-cache.txt needed due to upstream commit:
https://gitlab.com/samba-team/samba/-/commit/f7e31127e7f8beb12294c5187cca9e191589ddcc

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/samba4/samba4-cache.txt

@@ -44,3 +44,4 @@ Checking value of GNUTLS_CIPHER_AES_128_CFB8: 29
 Checking value of GNUTLS_MAC_AES_CMAC_128: 203
 Checking whether fcntl supports flags to send direct I/O availability signals: OK
 Checking for gnutls fips mode support: NO
+Checking for readlink breakage: NO

package/samba4/samba4.hash

@@ -1,4 +1,4 @@
 # Locally calculated after checking pgp signature
-# https://download.samba.org/pub/samba/stable/samba-4.15.5.tar.asc
-sha256  69115e33831937ba5151be0247943147765aece658ba743f44741672ad68d17f  samba-4.15.5.tar.gz
+# https://download.samba.org/pub/samba/stable/samba-4.15.6.tar.asc
+sha256  0575b999a9048445820428dc540ba8a9527ce596fa66af02ea2ba1ea9578bcb4  samba-4.15.6.tar.gz
 sha256  8ceb4b9ee5adedde47b31e975c1d90c73ad27b6b165a1dcd80c7c545eb65b903  COPYING

package/samba4/samba4.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-SAMBA4_VERSION = 4.15.5
+SAMBA4_VERSION = 4.15.6
 SAMBA4_SITE = https://download.samba.org/pub/samba/stable
 SAMBA4_SOURCE = samba-$(SAMBA4_VERSION).tar.gz
 SAMBA4_INSTALL_STAGING = YES