posix.cfg: Fixed wrong arg number

Author: orbitcowboy

cfg/posix.cfg

@@ -1652,7 +1652,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <not-bool/>
       <valid>0:</valid>
     </arg>
-    <arg nr="3" direction="in">
+    <arg nr="2" direction="in">
       <not-uninit/>
       <not-bool/>
       <minsize type="value" value="2"/>