Move the global variables representing each Target behind accessor function

This avoids "static initialization order fiasco"

Differential Revision: https://reviews.llvm.org/D25412

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283702 91177308-0d34-0410-b5e6-96231b3b80d8
102 files changed