Style/MutableConstant gives false positive on splat assignment

[Drenmi]

As per this StackOverflow post, when running this cop on a piece of code with a splat assignment, it incorrectly reports a violation.

Example:

FOO = *(1...10)

Expected behavior

No offenses are registered.

Actual behavior

C: Freeze mutable objects assigned to constants.
NUMS = *(1...10)
       ^^^^^^^^^

Steps to reproduce the problem

Run:

bundle exec rubocop --only Style/MutableConstant

on the above code.

RuboCop version

$ rubocop -V
0.42.0 (using Parser 2.3.1.2, running on ruby 2.3.0 x86_64-darwin15)