tdb2: Make TDB1 use the same tdb_hash() wrapper as TDB2

tdb2: Make TDB1 use the same tdb_hash() wrapper as TDB2

This means converting the tdb1 inbuilt hash functions to the
tdb2-style, so they return 64 bit.  We truncate to 32 bit everywhere
but in tdb_check() which needs to do so explicitly.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(Imported from CCAN commit 3e46dde21261966941469a6c75e1b45cd2d26324)