package/proftpd: add pcre2 optional dependency

pcre2 is an optional dependency since version 1.3.8 and
https://github.com/proftpd/proftpd/commit/e63cf016f574890c4096d587b8b1f55d87ac05d5

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

package/proftpd/proftpd.mk

@@ -31,6 +31,13 @@ ifeq ($(BR2_PACKAGE_LIBIDN2),y)
 PROFTPD_DEPENDENCIES += libidn2
 endif
 
+ifeq ($(BR2_PACKAGE_PCRE2),y)
+PROFTPD_CONF_OPTS += --enable-pcre2
+PROFTPD_DEPENDENCIES += pcre2
+else
+PROFTPD_CONF_OPTS += --disable-pcre2
+endif
+
 ifeq ($(BR2_PACKAGE_PROFTPD_MOD_CAP),y)
 PROFTPD_CONF_OPTS += --enable-cap
 PROFTPD_DEPENDENCIES += libcap