gnu.cfg: Added support for pipe2().

cfg/gnu.cfg

@@ -54,6 +54,19 @@
       <not-bool/>
     </arg>
   </function>
+  <!-- int pipe(int fildes[2],int flags); -->
+  <function name="pipe">
+    <returnValue type="int"/>
+    <noreturn>false</noreturn>
+    <arg nr="1" direction="out">
+      <not-null/>
+      <not-bool/>
+      <minsize type="value" value="2"/>
+    </arg>
+    <arg nr="2" direction="in">
+      <not-uninit/>
+    </arg>
+  </function>
   <!-- void * xcalloc(size_t nitems, size_t size); -->
   <function name="xcalloc">
     <use-retval/>