wswrapper: update README, DO_MSG def for output.

Update README to mention wswrapper. Add DO_MSG define which controls
whether wswrapper code generates basic output.

utils/README.md

-## wsproxy: WebSockets to TCP Proxy
+## WebSockets Utilities: wswrapper and wsproxy
 
 
-### How it works
+### wswrapper
+
+wswrapper is an LD_PRELOAD library that converts a TCP listen socket
+of an existing program to a be a WebSockets socket. The `wswrap`
+script can be used to easily launch a program using wswrapper. Here is
+an example of using wswrapper with vncserver. wswrapper will convert
+the socket listening on port 5901 to be a WebSockets port:
+
+    `cd noVNC/utils`
+
+    `./wswrap 5901 vncserver -geometry 640x480 :1`
+
+
+### wsproxy
 
 At the most basic level, wsproxy just translates WebSockets traffic
 to normal socket traffic. wsproxy accepts the WebSockets handshake,
@@ -15,7 +28,7 @@ case the data from the client is not a full WebSockets frame (i.e.
 does not end in 255).
 
 
-### Additional features
+#### Additional wsproxy features
 
 These are not necessary for the basic operation.
 
@@ -38,7 +51,7 @@ These are not necessary for the basic operation.
   option.
 
 
-### Implementations
+#### Implementations of wsproxy
 
 There are three implementations of wsproxy included: python, C, and
 Node (node.js).

utils/wswrapper.c

@@ -13,6 +13,7 @@
  * - programs using ppoll or epoll will not work correctly
  */
 
+#define DO_MSG 1
 //#define DO_DEBUG 1
 //#define DO_TRACE 1
 
@@ -828,6 +829,7 @@ int _WS_poll(int mode, struct pollfd *fds, nfds_t nfds, int timeout,
     return ret;
 }
 
+
 /*
  * Overload (LD_PRELOAD) standard library network routines
  */

utils/wswrapper.h

@@ -7,6 +7,14 @@
  * wswrapper.so.
  */
 
+#ifdef DO_MSG
+#define MSG(...) \
+    fprintf(stderr, "wswrapper: "); \
+    fprintf(stderr, __VA_ARGS__);
+#else
+#define MSG(...)
+#endif
+
 #ifdef DO_DEBUG
 #define DEBUG(...) \
     if (DO_DEBUG) { \
@@ -27,10 +35,6 @@
 #define TRACE(...)
 #endif
 
-#define MSG(...) \
-    fprintf(stderr, "wswrapper: "); \
-    fprintf(stderr, __VA_ARGS__);
-
 #define RET_ERROR(eno, ...) \
     fprintf(stderr, "wswrapper error: "); \
     fprintf(stderr, __VA_ARGS__); \