Add signature to libmedia.so.

Also remove superflous data from libpackage.rdef

This should fix #15958

Change-Id: I76991030541dca12a2dfdd9282f02274a461ed2a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2561
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Package Kit: internationalize strings that may be displayed to the user

This fixes #14525.

Change-Id: I25810a4e12caed7aa47717e278591b1716b6198c
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2329
Reviewed-by: Niels Sascha Reedijk <niels.reedijk@gmail.com>