## Why this should be merged
The `vm.PrecompileEnvironment.Call()` method requires careful usage
because of reentrancy vulnerabilities (this is common to all outgoing
`CALL`s in the EVM, not just stateful precompiles). This package
provides a common method of protection, a reentrancy guard.
## How this works
Provides a function that returns `vm.ErrExecutionReverted` if called
twice, by the same contract, in the same transaction, with the same
identifier.
## How this was tested
Unit and integration tests.
