perl: fix creation and generate new perl-rdepends.txt

The creation of perl-rdepends.txt simply copied over the
generated list (perl-rdepends.generated) to perl-rdepends.txt
while missing out the manual dependencies placed in
perl-rdepends.inc. This caused missing runtime dependencies.
Additionally, the mechanism always appended which then
produced duplicated lines in perl-rdepends.txt if the creation
function is run multiple times.
We now concatenate both the .inc and .generated to the final
.txt so manual and generated both types of dependencies make
it to the final configuration. A new perl-rdepends.txt is then
generated with these fixes.

Signed-off-by: Awais Belal <awais_belal@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>