Sync from Automake, as follows:

Sync from Automake, as follows:

2006-05-11  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
* config/install-sh: Initialize IFS, so field splitting isn't
turned off later.
* config/mkinstalldirs: Likewise.
* config/missing: Remove superfluous quotes.  Replace all uses of
`[' by `test', for consistency, and for..
* config/missing (sed_minuso, sed_output): New variables.
(autom4te, help2man, makeinfo): Use them.  Unifies detection of
`-o FILE', `--output FILE', `--output=FILE', stricter regex.
Fixes `missing' to detect `--output' for help2man.  Fixes
PR automake/483.  Report by Dennis J. Linse.
(autom4te): Document in `missing --help'.