Revert "Fix allocations of SmallVector and SmallPtrSet so they are more prone to"

This reverts commit 61733090.

It broke the bots:

/home/clangbuild2/clang-ppc64-2/llvm.src/unittests/ADT/SmallVectorTest.cpp:150: PushPopTest
/home/clangbuild2/clang-ppc64-2/llvm.src/unittests/ADT/SmallVectorTest.cpp:118: Failure
Value of: v[i].getValue()
  Actual: 0
Expected: value
Which is: 2

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178334 91177308-0d34-0410-b5e6-96231b3b80d8