Fix PR6875:

This includes a patch by Roman Divacky to fix the initial crash.

Move the actual addition of passes from *PassManager::add to
*PassManager::addImpl.  That way, when adding printer passes we won't
recurse infinitely.

Finally, check to make sure that we are actually adding a FunctionPass
to a FunctionPassManager before doing a print before or after it.
Immutable passes are strange in this way because they aren't
FunctionPasses yet they can be and are added to the FunctionPassManager.

llvm-svn: 103425