systemd: add optional dependency on pcre2

systemd can use libpcre2 when available, so this commit adds the
detection of this library.

Signed-off-by: Jérémy Rosen <jeremy.rosen@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/systemd/systemd.mk

@@ -144,6 +144,13 @@ else
 SYSTEMD_CONF_OPTS += -Dgcrypt=false
 endif
 
+ifeq ($(BR2_PACKAGE_PCRE2),y)
+SYSTEMD_DEPENDENCIES += pcre2
+SYSTEMD_CONF_OPTS += -Dpcre2=true
+else
+SYSTEMD_CONF_OPTS += -Dpcre2=false
+endif
+
 ifeq ($(BR2_PACKAGE_SYSTEMD_JOURNAL_GATEWAY),y)
 SYSTEMD_DEPENDENCIES += libmicrohttpd
 SYSTEMD_CONF_OPTS += -Dmicrohttpd=true