LinkModulesTest.cpp: Use test-specific Ctx instead of getGlobalContext(). The global context might not be free'd. [vg_leak]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207535 91177308-0d34-0410-b5e6-96231b3b80d8
[CMake] Enable llvm/unittests/LinkerTests. It had not been enabled since r199354.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207536 91177308-0d34-0410-b5e6-96231b3b80d8
LinkModulesTest.cpp: Reformat.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207537 91177308-0d34-0410-b5e6-96231b3b80d8