main/samba: upgrade to 4.17.3

remove netdb-defines.patch, fixed upstream
use bundled pyldb
add lmdb-dev to makedepends
libldb-mdb-int-samba4.so is built only on 64bit arches
9 jobs for !41547 with try-samba-4.17.3 in 5 minutes and 50 seconds (queued for 1 second)
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