cmake: fix mbedtls build

Author: tsl0922

CMakeLists.txt

@@ -70,7 +70,8 @@ set(LINK_LIBS ${ZLIB_LIBRARIES} ${LIBWEBSOCKETS_LIBRARIES} ${JSON-C_LIBRARIES} $
 set (CMAKE_REQUIRED_INCLUDES ${INCLUDE_DIRS})
 include(CheckSymbolExists)
 check_symbol_exists(LWS_OPENSSL_SUPPORT "lws_config.h" LWS_OPENSSL_ENABLED)
-if(LWS_OPENSSL_ENABLED)
+check_symbol_exists(LWS_WITH_MBEDTLS "lws_config.h" LWS_MBEDTLS_ENABLED)
+if(LWS_OPENSSL_ENABLED AND NOT LWS_MBEDTLS_ENABLED)
     find_package(OpenSSL REQUIRED)
     list(APPEND INCLUDE_DIRS ${OPENSSL_INCLUDE_DIR})
     list(APPEND LINK_LIBS ${OPENSSL_LIBRARIES})