example/delayed_echo: Fix bogus compiler warning

An std::array size may be uninitialized? ok...
```
../example/delayed_echo.cpp: In lambda function:
../example/delayed_echo.cpp:46:29: error: ‘buffer’ may be used uninitialized [-Werror=maybe-uninitialized]
   46 |         ssize_t bytes = read(fd, buffer.data(), std::size(buffer));
      |                         ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/11/array:41,
                 from ../example/delayed_echo.cpp:6:
/usr/include/c++/11/bits/range_access.h:245:5: note: by argument 1 of type ‘const std::array<char, 4096>&’ to ‘constexpr decltype (__cont.size()) std::size(const _Container&) [with _Container = std::array<char, 4096>]’ declared here
  245 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
../example/delayed_echo.cpp:45:32: note: ‘buffer’ declared here
   45 |         std::array<char, 4096> buffer;
```

Change-Id: I534dcfe5c4e2b843a061066548d8a4f9e6f9cc6f
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/example/delayed_echo.cpp b/example/delayed_echo.cpp
index e7fc33b..db90523 100644
--- a/example/delayed_echo.cpp
+++ b/example/delayed_echo.cpp
@@ -43,7 +43,7 @@
 
     auto ioCb = [&](IO&, int fd, uint32_t) {
         std::array<char, 4096> buffer;
-        ssize_t bytes = read(fd, buffer.data(), buffer.size());
+        ssize_t bytes = read(fd, buffer.data(), 4096);
         if (bytes <= 0)
         {
             printf("%s", content.c_str());