Remove a useless assignment in nxt_fs_mkdir_all().

This was reported by the 'Clang Static Analyzer' as a 'dead nested
assignment'.

We set end outside the loop but the first time we use it is to assign it
in the loop (not used anywhere else).

Further cleanup could be to reduce the scope of end by moving its
declaration inside the loop.

Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

src/nxt_fs.c

@@ -20,7 +20,7 @@ nxt_fs_mkdir_all(const u_char *dir, mode_t mode)
     nxt_assert(dirlen < PATH_MAX && dirlen > 1 && dir[0] == '/');
 
     dst = path;
-    start = end = (char *) dir;
+    start = (char *) dir;
 
     while (*start != '\0') {
         if (*start == '/') {