nghttpx: Remove unused

src/shrpx.h

@@ -44,6 +44,4 @@
 
 #define DIE() exit(EXIT_FAILURE)
 
-#define SHRPX_READ_WATERMARK (16 * 1024)
-
 #endif // SHRPX_H

src/shrpx_http2_session.h

@@ -168,8 +168,6 @@ public:
     CONNECT_FAILING,
   };
 
-  static const size_t OUTBUF_MAX_THRES = 64 * 1024;
-
   enum {
     // Connection checking is not required
     CONNECTION_CHECK_NONE,