manually copy debugloc over to a new instruction in clone() instead

manually copy debugloc over to a new instruction in clone() instead
of calling getAllMetadata().  This is semantically identical, but doing
it this way avoids unpacking the DebugLoc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135173 91177308-0d34-0410-b5e6-96231b3b80d8