Fix some warnings in Linux

src/civetweb.c

@@ -1149,6 +1149,7 @@ typedef struct tagTHREADNAME_INFO {
 #pragma pack(pop)
 #elif defined(__linux__)
 #include <sys/prctl.h>
+#include <sys/sendfile.h>
 #endif
 
 #if ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 12)))
@@ -5245,7 +5246,7 @@ static void send_file_data(struct mg_connection *conn,
 		mg_write(conn, filep->membuf + offset, (size_t)len);
 	} else if (len > 0 && filep->fp != NULL) {
 /* file stored on disk */
-#if defined(LINUX)
+#if defined(__linux__)
 		/* TODO (high): Test sendfile for Linux */
 		if (conn->throttle == 0 && conn->ssl == 0) {
 			off_t sf_offs = (off_t)offset;

src/main.c

@@ -127,7 +127,7 @@ static struct tuser_data
 #endif
 
 /* backup config file */
-#if !defined(CONFIG_FILE2) && defined(LINUX)
+#if !defined(CONFIG_FILE2) && defined(__linux__)
 #define CONFIG_FILE2 "/usr/local/etc/civetweb.conf"
 #endif
 

src/mod_lua.inl

@@ -1572,6 +1572,8 @@ static void lua_websocket_close(struct mg_connection *conn, void *ws_arg)
 	/* TODO: Delete lua_websock_data and remove it from the websocket list.
 	   This must only be done, when all connections are closed, and all
 	   asynchronous operations and timers are completed/expired. */
+	(void)shared_websock_list; /* shared_websock_list unused (see open TODO) */
+
 	(void)pthread_mutex_unlock(&ws->ws_mutex);
 }
 #endif