[llvm-xray] Store offset pointers in temporaries

DataExtractor::getU64 modifies the OffsetPtr which also pass to
RelocateOrElse which breaks on Windows. This addresses the issue
introduced in r349120.

Differential Revision: https://reviews.llvm.org/D55689

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349129 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed