Reading from a garbage pointer should be modeled as garbage,
and performTrivialCopy should be able to deal with any SVal input.

Patch by Ilya Palachev!

Differential Revision: https://reviews.llvm.org/D25727


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@285640 91177308-0d34-0410-b5e6-96231b3b80d8