Fix #1738

Author: yhirose

httplib.h

@@ -3860,11 +3860,7 @@ inline bool read_content_without_length(Stream &strm,
   uint64_t r = 0;
   for (;;) {
     auto n = strm.read(buf, CPPHTTPLIB_RECV_BUFSIZ);
-    if (n < 0) {
-      return false;
-    } else if (n == 0) {
-      return true;
-    }
+    if (n <= 0) { return true; }
 
     if (!out(buf, static_cast<size_t>(n), r, 0)) { return false; }
     r += static_cast<uint64_t>(n);