package/syslog-ng: add optional support for libcap

When libcap was compiled before, syslog-ng will use it as optional
dependency:

$ output/host/usr/bin/x86_64-linux-readelf -a output/target/usr/sbin/syslog-ng | grep NEEDED | sort
 0x0000000000000001 (NEEDED)             Shared library: [libcap.so.2]
[...]

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

package/syslog-ng/syslog-ng.mk

@@ -20,6 +20,13 @@ ifeq ($(BR2_PACKAGE_BUSYBOX),y)
 SYSLOG_NG_DEPENDENCIES += busybox
 endif
 
+ifeq ($(BR2_PACKAGE_LIBCAP),y)
+SYSLOG_NG_DEPENDENCIES += libcap
+SYSLOG_NG_CONF_OPTS += --enable-linux-caps
+else
+SYSLOG_NG_CONF_OPTS += --disable-linux-caps
+endif
+
 ifeq ($(BR2_PACKAGE_PYTHON),y)
 SYSLOG_NG_DEPENDENCIES += python
 SYSLOG_NG_CONF_OPTS += \