Refactoring SimplifyLibCalls to remove static initializers and generally cleaning up the code.

Summary: This eliminates ~200 lines of code mostly file scoped struct definitions that were unnecessary.

Reviewers: chandlerc, resistor

Reviewed By: resistor

Subscribers: morisset, resistor, llvm-commits

Differential Revision: http://reviews.llvm.org/D5364

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217982 91177308-0d34-0410-b5e6-96231b3b80d8