[krbdev.mit.edu #5819] copyfiles.xml vs 64-bit builds

[Jeffrey Altman via RT]

copyfiles.xml contains a hardcoded list of file names.

Some files such as krb5_32.dll and krb5_32.lib have different names when
building for 64-bit.  For example, krb5_64.dll and krb5_64.lib. 

Some files, such as the Kerberos v4 library are never installed on
64-bit systems and will not be installed in future 32-bit builds.

When constructing the staging area from copyfiles.xml, the copy will
fail because files that are not built are not found.

One possible approach to address this:  Add an additional property to
the File entries specifying component names and then selectively enable
or disable components by the CPU type of the build.