[PlaceSafepoints] Stop special casing some intrinsics

[PlaceSafepoints] Stop special casing some intrinsics

We were special casing a handful of intrinsics as not needing a safepoint before them.  After running into another valid case - memset - I took a closer look and realized that almost no intrinsics need to have a safepoint poll before them.  Restructure the code to make that apparent so that we stop hitting these bugs.  The only intrinsics which need a safepoint poll before them are ones which can run arbitrary code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237744 91177308-0d34-0410-b5e6-96231b3b80d8