std.cfg: Fixed configuration of mbstowcs

cfg/std.cfg

@@ -2364,7 +2364,7 @@
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1" direction="out">
-      <not-uninit indirect="1"/>
+      <not-uninit/>
     </arg>
     <arg nr="2" direction="in">
       <not-null/>

test/cfg/std.c

@@ -1759,6 +1759,9 @@ void uninitvar_mbstowcs(wchar_t* d, const char* s, size_t m)
 
     // No warning is expected
     (void)mbstowcs(d,s,m);
+
+    wchar_t buf[100];
+    (void)mbstowcs(buf,s,100);
 }
 
 void uninitvar_mbsrtowcs(wchar_t* d, const char** s, size_t m, mbstate_t *p)