package/rsyslog: add impcap support

impcap is available since version 8.2006.0 and only depends on libpcap:
https://github.com/rsyslog/rsyslog/commit/76318ad9269309d0423358c545f72f3f79c12203

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

package/rsyslog/rsyslog.mk

@@ -30,7 +30,6 @@ RSYSLOG_CONF_OPTS += --disable-elasticsearch \
 	--disable-omhttp \
 	--disable-fmhttp \
 	--disable-imdocker \
-	--disable-impcap \
 	--disable-omhttpfs \
 	--disable-mmkubernetes
 
@@ -60,6 +59,13 @@ else
 RSYSLOG_CONF_OPTS += --disable-libgcrypt
 endif
 
+ifeq ($(BR2_PACKAGE_LIBPCAP),y)
+RSYSLOG_DEPENDENCIES += libpcap
+RSYSLOG_CONF_OPTS += --enable-impcap
+else
+RSYSLOG_CONF_OPTS += --disable-impcap
+endif
+
 ifeq ($(BR2_PACKAGE_MYSQL),y)
 RSYSLOG_DEPENDENCIES += mysql
 RSYSLOG_CONF_OPTS += --enable-mysql