title: getting "implicit declaration of function 'fcloseall' is invalid in C99" when compiling to gnu99
body: <p>Consider the following C code:</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  void fatal(const char* message){
   /*
    Prints a message and terminates the program.
    Closes all open i/o streams before exiting.
   */
   printf("%s\n", message);
   fcloseall();
   exit(EXIT_FAILURE);
  }
  </code></pre>
  
  <p>I'm using clang 2.8 to compile: <code>clang -Wall -std=gnu99 -o &lt;executable&gt; &lt;source.c&gt;</code></p>
  
  <p>And get: <code>implicit declaration of function 'fcloseall' is invalid in C99</code></p>
  
  <p>Which is true, but i'm explicitly compiling to gnu99 [which should support fcloseall()], and not to c99.
  Although the code runs, I don't like to have unresolved warnings when compiling.
  How can i solve this?</p>
  
  <p><strong>Edit</strong>: corrected tipo.</p>