package/libmatroska: bump to version 1.7.1

C++14 is mandatory since version 1.7.0 and
https://github.com/Matroska-Org/libmatroska/commit/7263bbaac134a20a79dfe7bd23b364fcd1a588cc

https://github.com/Matroska-Org/libmatroska/blob/release-1.7.1/NEWS.md

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libmatroska/Config.in

@@ -2,7 +2,7 @@ config BR2_PACKAGE_LIBMATROSKA
 	bool "libmatroska"
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_USE_WCHAR
-	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # libebml
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # C++14
 	select BR2_PACKAGE_LIBEBML
 	help
 	  Extensible open standard audio/video container format access

package/libmatroska/libmatroska.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  daf91a63f58dd157ca340c457871e66260cb9c3333fefb008b318befbb0e081a  libmatroska-1.6.3.tar.xz
+sha256  572a3033b8d93d48a6a858e514abce4b2f7a946fe1f02cbfeca39bfd703018b3  libmatroska-1.7.1.tar.xz
 sha256  dc626520dcd53a22f727af3ee42c770e56c97a64fe3adb063799d8ab032fe551  LICENSE.LGPL

package/libmatroska/libmatroska.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBMATROSKA_VERSION = 1.6.3
+LIBMATROSKA_VERSION = 1.7.1
 LIBMATROSKA_SOURCE = libmatroska-$(LIBMATROSKA_VERSION).tar.xz
 LIBMATROSKA_SITE = http://dl.matroska.org/downloads/libmatroska
 LIBMATROSKA_INSTALL_STAGING = YES