[CodeGen] Mark EVT:getExtendedSizeInBits() as LLVM_READONLY.

I think I had tried this a long time back and some bots failed. Hoping that was with an older gcc and maybe now it will work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264840 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed