[PATCH] add a few new xfuns and use them as appropriate

[Denis Vlasenko]

Hi,

We have a lot of this:

if (stat(old_path, &stat_buf) < 0)
    bb_error_msg_and_die("Couldn't stat file %s", old_path);

xstat() would make it smaller. These patches do that.

Patches are posted as replies. Please apply.
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vda