Remove the dependency on CPAN module List::MoreUtils

[underwoo]

Description
The Perl script split_ncvars.pl uses a CPAN module List::MoreUtils for a single function uniq. The use of this function can be removed using a better method to grab the intersection of two arrays:

my @array1 = ["val1", "val2", "val3"];
my @array2 = ["val1", "val3", "val4"];
my %arr1 = map { $_ => () } @array1
my @intersection = grep { exists $arr1{$_} } @array2;

This assumes the values in @array1 and @array2 are unique. Since the arrays in split_ncvars.pl hold dimensions, the lists should be unique.

How Has This Been Tested?
The split_ncvars.pl tests are run, which indicates the output is identical to previous runs.

This PR should be taken after #331.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes