[Constant Hoisting] Extend coverage of the constant hoisting pass.

This commit extends the coverage of the constant hoisting pass, adds additonal
debug output and updates the function names according to the style guide.

Related to <rdar://problem/16381500>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204389 91177308-0d34-0410-b5e6-96231b3b80d8