package/libcpprestsdk: add optional websocketpp dependency

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

package/libcpprestsdk/libcpprestsdk.mk

@@ -10,6 +10,13 @@ LIBCPPRESTSDK_LICENSE = MIT
 LIBCPPRESTSDK_LICENSE_FILES = license.txt
 LIBCPPRESTSDK_SUBDIR = Release
 LIBCPPRESTSDK_DEPENDENCIES += host-pkgconf boost openssl zlib
-LIBCPPRESTSDK_CONF_OPTS = -DWERROR=OFF -DCPPREST_EXCLUDE_WEBSOCKETS=ON
+LIBCPPRESTSDK_CONF_OPTS = -DWERROR=OFF
+
+ifeq ($(BR2_PACKAGE_WEBSOCKETPP),y)
+LIBCPPRESTSDK_DEPENDENCIES += websocketpp
+LIBCPPRESTSDK_CONF_OPTS += -DCPPREST_EXCLUDE_WEBSOCKETS=OFF
+else
+LIBCPPRESTSDK_CONF_OPTS += -DCPPREST_EXCLUDE_WEBSOCKETS=ON
+endif
 
 $(eval $(cmake-package))