Make static variables const if possible. Makes them go into a read-only section.

Make static variables const if possible. Makes them go into a read-only section.

Or fold them into a initializer list which has the same effect. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231598 91177308-0d34-0410-b5e6-96231b3b80d8