posix.cfg: Improved support for overlapping data check

cfg/posix.cfg

@@ -5266,6 +5266,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <returnValue type="void"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <not-overlapping-data ptr1-arg="1" ptr2-arg="2" size-arg="3"/>
     <arg nr="1" direction="in">
       <not-uninit/>
       <minsize type="argvalue" arg="3"/>