[opaque pointer types] Pass function types to CallInst creation.

[opaque pointer types] Pass function types to CallInst creation.

This cleans up all CallInst creation in LLVM to explicitly pass a
function type rather than deriving it from the pointer's element-type.

Differential Revision: https://reviews.llvm.org/D57170

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@352909 91177308-0d34-0410-b5e6-96231b3b80d8