Inliner should not add callgraph edges for intrinsic calls (PR22857)

The CallGraphNode function "addCalledFunction()" asserts that edges are not to intrinsics.

This patch makes sure that the Inliner does not add such an edge to the callgraph.

Fix for clang crash by assertion: https://llvm.org/bugs/show_bug.cgi?id=22857

Differential Revision: http://reviews.llvm.org/D8231

llvm-svn: 231927