Optimization: Compare strings to a null string directly

[johnsonjh]

• Small run-time optimization

[cjdelisle]

conflicts, not worth my time to fix, shouldn't really be worth your time either

[johnsonjh]

Not really any of my time at all, I believe these were automatically applied by some linter/checker or another. I normally run all the sources through a small battery of them, so, no real time of mine inovlved - leave open for now, and if it picks it up again, I'll submit rebased - but yeah, if I have to do it manually, it's such a small optimization that I won't bother.

[johnsonjh]

@cjdelisle autorebased

[johnsonjh]

• • Verified clean merge with recursive strategy against develop as of Thu Nov 26 02:01:32 PM EST 2020 + PR Improvement in bbolt/walletdb speed #111 + PR More reliably detect if we are current (or not.) #142 + PR Fix bug where pktctl -h would show help twice. #151 + PR blockchain: Avoid deadlock with additional locking #156 + PR peer: Default to 1s default trickle interval #160

Auto-merging config.go
Merge made by the 'recursive' strategy.
 cmd/pktctl/pktctl.go           | 2 +-
 config.go                      | 2 +-
 integration/rpctest/btcd.go    | 2 +-
 neutrino/cache/lru/lru_test.go | 2 +-
 neutrino/query_test.go         | 2 +-
 pktconfig/version/version.go   | 2 +-
 txscript/reference_test.go     | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

[johnsonjh]

• NOTE: Applied to WIP rebase branch successfully.