package.bbclass: Fix populate_packages for glob expansion issues

package.bbclass: Fix populate_packages for glob expansion issues

If we put a valid glob like "*/foo/*" into FILES, populate_packages
breaks with a "file exists" message. This is because the glob expansion
does not have "./" prefix however there may already be an entry in
the seen list which does have such a prefix. The easiest/simplest fix
right now is to add the prefix if it doesn't exist which only happens
for certain globs.

(From OE-Core rev: 138c5f3af892e33f576fc7dd268e122b179f82a1)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>