Revert "Adding object caching support to MCJIT"

This reverts commit 07f03923137a91e3cca5d7fc075a22f8c9baf33a.

Looks like it broke the valgrind bot:

http://lab.llvm.org:8011/builders/llvm-x86_64-linux-vg_leak/builds/649

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180249 91177308-0d34-0410-b5e6-96231b3b80d8