During installation of a target we generate "tweak" rules to update the
installed file (RPATH, strip, ranlib, etc.).  However, some targets
install multiple files, such as the versioned names of a shared library.

Previously the extra files for a target have always been symbolic links,
but for cross-compiling from Windows to UNIX they may need to be copies.
This commit teaches the generated install scripts to loop over all files
installed for the target to apply tweaks to those that are not symlinks.

See issue #9171.