package/civetweb: add zlib optional dependency

zlib is an optional dependency since version 1.11 and
https://github.com/civetweb/civetweb/commit/6b8b15935378f71323ff95f907fa0d33841deac0

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

package/civetweb/civetweb.mk

@@ -38,6 +38,12 @@ else
 CIVETWEB_COPT += -DNO_SSL
 endif
 
+ifeq ($(BR2_PACKAGE_ZLIB),y)
+CIVETWEB_CONF_OPTS += WITH_ZLIB=1
+CIVETWEB_LIBS += -lz
+CIVETWEB_DEPENDENCIES += zlib
+endif
+
 ifeq ($(BR2_PACKAGE_CIVETWEB_SERVER),y)
 CIVETWEB_BUILD_TARGETS += build
 CIVETWEB_INSTALL_TARGETS += install