posix.cfg: Added support for the fileno() function.

cfg/posix.cfg

@@ -2535,6 +2535,16 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <not-null/>
     </arg>
   </function>
+  <!-- int fileno(FILE *stream);-->
+  <function name="fileno">
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <arg nr="1">
+      <not-null/>
+      <not-uninit/>
+    </arg>
+  </function>
   <memory>
     <alloc init="true">strdup</alloc>
     <alloc init="true">strndup</alloc>