package.bbclass: only one hardlink of separated debug info file in each directory

package.bbclass: only one hardlink of separated debug info file in each directory

While multiple hardlinks of binary located in different dirs,
there are also multiple hardlinks of separated debug info file
with the same binary name in same debug dirs. But in each dir,
only one debug file with original name works. Because all of
binary hardlinks have one `.gnu_debuglink' which is added in
`splitdebuginfo'. It caused gdb could not find debugging
symbols.

[Before the patch]
$ find .
./usr/bin/foo
./usr/bin/foo-hd1
./usr/bin/.debug
./usr/bin/.debug/foo
./usr/bin/.debug/foo-hd1
./usr/libexec/foo-hd2
./usr/libexec/.debug
./usr/libexec/.debug/foo-hd2

$ readelf --debug-dump usr/libexec/foo-hd2
Contents of the .gnu_debuglink section:
  Separate debug info file: foo

$ gdb usr/libexec/foo-hd2
Reading symbols from usr/libexec/foo-hd2...(no debugging symbols found)...done.
[Before the patch]

[Apply the patch]
$ find .
./usr/bin/foo
./usr/bin/foo-hd1
./usr/bin/.debug
./usr/bin/.debug/foo
./usr/libexec/foo-hd2
./usr/libexec/.debug
./usr/libexec/.debug/foo

$ gdb usr/libexec/foo-hd2
Reading symbols from usr/libexec/foo-hd2...Reading symbols from usr/libexec/.debug/foo...done.
[Apply the patch]

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>