posix.cfg: Added support for readdir().

cfg/posix.cfg

@@ -169,6 +169,14 @@
       <not-uninit/>
     </arg>
   </function>
+  <function name="readdir">
+    <noreturn>false</noreturn>
+    <arg nr="1">
+      <not-null/>
+      <not-uninit/>
+    </arg>
+    <leak-ignore/>
+  </function>
   <function name="rand_r">
     <noreturn>false</noreturn>
     <leak-ignore/>

test/testnullpointer.cpp

@@ -2665,6 +2665,9 @@ private:
               "  strdup(x);\n"
               "}");
         ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: x\n", errout.str());
+
+        check("DIR* f(){ DIR *dirp = 0; return readdir (dirp);}");
+        ASSERT_EQUALS("[test.cpp:1]: (error) Possible null pointer dereference: dirp\n",errout.str());
     }
 };