For each function that we optimize we initialize a new list of lib functions. For each function name we malloc memory. This patch changes the Libcall map to use BumpPtrAllocator. Now we malloc only once. This speeds up instcombine by a few % on a large c++ program.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176170 91177308-0d34-0410-b5e6-96231b3b80d8