msvc: change the handling of system lib cache.
msvc: change the handling of system lib cache.

We really spend a lot of time in this.  Use a file, it is safer
with \n.

	* msvc/link.exe (handle_lib): Use a cache file.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport