package/jack2: disable example tools

Disable example tools (enabled by default since bump to version 1.9.20
in commit 26ca7fec041836c31f29c5566365fe40eb552bca and
https://github.com/jackaudio/jack2/commit/508d95a97e0cdfad2e8c7d6cdd478741fdba2c87)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/jack2/jack2.mk

@@ -12,7 +12,7 @@ JACK2_CPE_ID_VENDOR = jackaudio
 JACK2_DEPENDENCIES = alsa-lib
 JACK2_INSTALL_STAGING = YES
 
-JACK2_CONF_OPTS = --alsa
+JACK2_CONF_OPTS = --alsa --example-tools=no
 
 ifeq ($(BR2_PACKAGE_LIBEXECINFO),y)
 JACK2_DEPENDENCIES += libexecinfo