* lib/install-sh: Sync from Autoconf, as follows:

* lib/install-sh: Sync from Autoconf, as follows:
Don't use 'path' to talk about file names,
as per GNU coding standards.  Close a race condition reported by Ralf
Wildenhues and Stepan Kasal.  There is still a race condition
on hosts that predate Posix 1003.1-1992, but we can't help this.
Don't mishandle weird characters like space on pre-Posix hosts.
Invoke mkdir at most once per dir arg on pre-Posix hosts.