package/clamav: add optional dependency to pcre2

Upstream recommends pcre2 over pcre:
https://github.com/Cisco-Talos/clamav-devel/commit/1f71c2b21ccaef412280471444f4d01ec9b8099d

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/clamav/clamav.mk

@@ -76,7 +76,10 @@ else
 CLAMAV_CONF_OPTS += --without-iconv
 endif
 
-ifeq ($(BR2_PACKAGE_PCRE),y)
+ifeq ($(BR2_PACKAGE_PCRE2),y)
+CLAMAV_CONF_OPTS += --with-pcre=$(STAGING_DIR)/usr
+CLAMAV_DEPENDENCIES += pcre2
+else ifeq ($(BR2_PACKAGE_PCRE),y)
 CLAMAV_CONF_OPTS += --with-pcre=$(STAGING_DIR)/usr
 CLAMAV_DEPENDENCIES += pcre
 else