posix.cfg: Removed invalid argument checks from functions that accept 'AT_FDCWD', which set to -100 on some systems.

cfg/posix.cfg

@@ -456,7 +456,6 @@
     <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1" direction="in">
-      <valid>0:</valid>
       <not-uninit/>
     </arg>
     <arg nr="2" direction="in">
@@ -969,7 +968,6 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <leak-ignore/>
     <arg nr="1" direction="in">
       <not-uninit/>
-      <valid>0:</valid>
     </arg>
     <arg nr="2" direction="in">
       <not-null/>