Replace copypasta with function calls to make tests intelligible.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208111 91177308-0d34-0410-b5e6-96231b3b80d8
Remove meaningless return value in test.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208112 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify unit test code.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208116 91177308-0d34-0410-b5e6-96231b3b80d8