base-files: return success on lib-copying with external toolchain when using an exter...

base-files: return success on lib-copying with external toolchain when using an external toolchain the base-files package copies libc, libgcc and others from the library directory.

The file list is given as following in the .config:
CONFIG_LIBC_FILE_SPEC="./lib/ld{-*.so,-linux*.so.*} ./lib/lib{anl,c,cidn,crypt,dl,m,nsl,nss_dns,nss_files,resolv,util}{-*.so,.so.*}"

Because the filenames are composed with different endings, not all files exist
and will be skipped. Currently, this works only if the last composed file
(util.so.*) really exists. At the moment this works - but only if you don't add
a new file like 'uClibc'.

Adding it at the end '...resolv,util,uClibc}{-*.so,.so.*}' will lead to this
message, because the combination 'libuClibc.so.*' doesn't exist and Make will
evaluate the last copy statement of the for loop.