Make all the Function implementations different so the compiler won't share them.

Clang on ARM64 was making the three Function methods with identical bodies have
one implementation that was shared.  That threw off the count of breakpoints, since
we don't count as separate locations three functions with the same address.

I also cleaned up the test case while I was at it.

<rdar://problem/27001915>

llvm-svn: 279800