[lldbsuite] The test inside TestOverloadedFunctions.py has the wrong class name

Summary: It looks like the test file was copied from TestCPPStaticMethods.py because they have the same name. This means that the two tests will try to write to the same output files and will either overwrite each other's output or occasionally cause failures because they can't both access the same file.

Reviewers: asmith, zturner

Reviewed By: zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49261

llvm-svn: 336960