Support ESP8266 TCP stack config

Use the ESP8266 network stack configuration values if they are present
and the  ESP32 defines are missing.

Fixes #343

Author: willmmiles

src/WebResponseImpl.h

@@ -16,9 +16,13 @@
 #include "./literals.h"
 
 #ifndef CONFIG_LWIP_TCP_MSS
+#ifdef TCP_MSS  // ESP8266
+#define CONFIG_LWIP_TCP_MSS TCP_MSS
+#else
 // as it is defined for ESP32's Arduino LWIP
 #define CONFIG_LWIP_TCP_MSS 1436
 #endif
+#endif
 
 #define ASYNC_RESPONCE_BUFF_SIZE CONFIG_LWIP_TCP_MSS * 2
 // It is possible to restore these defines, but one can use _min and _max instead. Or std::min, std::max.

src/WebResponses.cpp

@@ -10,9 +10,13 @@
 #include <utility>
 
 #ifndef CONFIG_LWIP_TCP_WND_DEFAULT
+#ifdef TCP_WND  // ESP8266
+#define CONFIG_LWIP_TCP_WND_DEFAULT TCP_WND
+#else
 // as it is defined for esp32's LWIP
 #define CONFIG_LWIP_TCP_WND_DEFAULT 5760
 #endif
+#endif
 
 using namespace asyncsrv;