Fix two CFG_TOYBOX_SUID corner cases:

1) Don't try to force re-exec unless we actually dropped permissions.
   (Fixes "./toybox mount" when no suid bit on toybox binary, which
   previously exited.)
2) Set temporary toys.which value for error reporting.
   (Fixes "ln -s toybox mount && ./mount" with CFG_TOYBOX_DEBUG and
   no suid bit, which previously segfaulted.)
2 files changed