Signed-off-by: Richa Banker <[email protected]>

Backport concurrent_test.go to release-1.3 branch

As per `go build -gcflags -m ./... 2>&1`:

Old behaviour:
```
./bucket.go:148:31: leaking param: key
./bucket.go:192:42: leaking param: key
./bucket.go:271:22: leaking param: key
```

Now:
```
./bucket.go:148:31: key does not escape
./bucket.go:192:42: key does not escape
./bucket.go:271:22: key does not escape
```

Signed-off-by: Evgenii Stratonikov <[email protected]>
(cherry picked from commit 71a59ca)
Signed-off-by: Wei Fu <[email protected]>

Signed-off-by: Wei Fu <[email protected]>
(cherry picked from commit 324df9c)
Signed-off-by: Wei Fu <[email protected]>

Signed-off-by: Wei Fu <[email protected]>
(cherry picked from commit 1b08078)
Signed-off-by: Wei Fu <[email protected]>

Application might change key value after seeking and before real put.
This unexpected behaviour could corrupt database. When users file issue,
maintainers doesn't know application behaviour. It could be caused by
data race. This patch is to prevent such case and save maintainers' time.

Signed-off-by: Wei Fu <[email protected]>
(cherry picked from commit a05ec68)
Signed-off-by: Wei Fu <[email protected]>

It's follow-up of #637.

Signed-off-by: Wei Fu <[email protected]>
(cherry picked from commit 62d8026)
Signed-off-by: Wei Fu <[email protected]>

[1.3] bucket.Put: copy key before seek

Signed-off-by: Mustafa Elbehery <[email protected]>

[1.3] Fix `bbolt keys` and `bbolt get` to prevent them from panicking when no parameter provided