r22727 dead code (Coverity CID 47)

Hi Erik,

r22727 adjusted svn_wc_transmit_text_deltas2() to remove the only
non-NULL assignment to the entry_digest_hex local variable, but retained
optional validation of that (now always NULL) entry checksum against the
calculated checksum.

I _think_ that the whole section starting "Make sure the old text base
still matches its checksum" can now be removed (along with the
entry_digest_hex variable) because it seems to be covered by the code
above added in that revision, but I'm not familiar enough with the code
to know for sure.

[This is Coverity CID 47, by the way].

Also, while we're there, you also (in the same revision) removed the
localfile local variable but _added_ a commented-out svn_io_file_close()
call with that variable (after the comment "Close the two files");
I'm assuming that's just cruft?

Regards,
Malcolm