install: cope with non-injective $(transform).

install: cope with non-injective $(transform).

* lib/am/progs.am (install-%DIR%PROGRAMS): Rewrite rule to not
try to use the installed name as key in a hash, so destructive
$(transform) scripts still work.
* lib/am/scripts.am (install-%DIR%SCRIPTS): Likewise.
* tests/transform.test: Fix test to look in right place for
installed files.
* tests/transform2.test: New test.
* tests/Makefile.am: Adjust.
Report by Jim Meyering.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>