[test] Fix two testcases. NFC.

Trivial fix for two testcases. When Polly isn't linked into opt,
independent of whether it's built in-tree or not, these testcases forget
to load the appropriate library.

Contributed-by: Philip Pfaffe <philip.pfaffe@gmail.com>

Differential Revision: https://reviews.llvm.org/D31596

llvm-svn: 299357