[Chapel Merge] Add skipif to the directory tracking deprecated Bi

Branch: refs/heads/master
Revision: 6472431
Author: lydia-duncan
Log Message:

Merge pull request #17874 from lydia-duncan/addGMPSkipif

Add skipif to the directory tracking deprecated BigInteger symbols
[trivial, unreviewed]

BigInteger relies on GMP, so no tests in that directory should run when GMP is
not available.

Verified a fresh checkout behaved correctly with and without CHPL_GMP

Modified Files:
A test/deprecated/BigInteger.skipif

Compare: https://github.com/chapel-lang/chapel/compare/b6aca69ca8f1...64724310eafe