Revert "[ubsan] PR34266: When sanitizing the 'this' value for a member...

Revert "[ubsan] PR34266: When sanitizing the 'this' value for a member function that happens to be a lambda call operator, use the lambda's 'this' pointer, not the captured enclosing 'this' pointer (if any)."

This reverts commit r311589 because of bot breakage.
http://green.lab.llvm.org/green/job/clang-stage2-cmake-RgSan_check/4115/consoleFull#15752874848254eaf0-7326-4999-85b0-388101f2d404.

llvm-svn: 311680