Remove caching in FunctionImport: a Module can't be reused after being linked from

The Linker destroys the source module (API change coming to make it explicit)

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255064 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed