* x/evm/keeper: save 24B with Go in-condition variable idiom
The prior code doubly invoked (*ethereum/go-ethereum/core/types.Transaction).To()
which is quite expensive, and firstly copies 20 bytes each time, then
that gets rounded up to the proper size class/pointer alignment so on
64-bit machines 20B -> 24B.
Isolating a benchmark for this code per issue #826 shows this saves
quite a bit of bytes and some nano seconds which all count up towards
the transactions per seconds being processed:
```shell
$ benchstat before.txt after.txt
name old time/op new time/op delta
CopyAddr-8 38.4ns ± 3% 19.3ns ± 3% -49.66% (p=0.000 n=10+10)
name old alloc/op new alloc/op delta
CopyAddr-8 48.0B ± 0% 24.0B ± 0% -50.00% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
CopyAddr-8 2.00 ± 0% 1.00 ± 0% -50.00% (p=0.000 n=10+10)
```
Fixes#826
* changelog
* lint
* Revert stray changes that were used in testing
* rm log
Co-authored-by: Federico Kunze Küllmer <federico.kunze94@gmail.com>
