When we make mocks (which the next patch will do), these names cause a warning:
```
wallet/test/run-db.c:32:64: error: declaration of ‘bitcoind’ shadows a parameter [-Werror=shadow=compatible-local]
32 | void (*cb)(struct bitcoind *bitcoind UNNEEDED,
wallet/test/run-db.c:30:53: note: shadowed declaration is here
30 | struct bitcoind *bitcoind UNNEEDED,
wallet/test/run-db.c:33:51: error: declaration of ‘height’ shadows a parameter [-Werror=shadow=compatible-local]
33 | u32 height UNNEEDED,
wallet/test/run-db.c:31:40: note: shadowed declaration is here
31 | u32 height UNNEEDED,
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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