[bugpoint] Reduce metadata that does not contribute to crash.

[fhahn]

Summary

Add a new reducer that drops metadata that does not contribute to the
crash from instructions.

It adjusts the metadata.ll test case, as now also the instruction level
metadata will get dropped.

[fhahn]

Fix typo

[reames]

llvm/tools/bugpoint-passes/TestPasses.cpp

178

*range* metadata

llvm/tools/bugpoint/CrashDebugger.cpp

852

Er, it really looks like you should be iterating the instruction set above?

[fhahn]

Update patch to retain metadata for selected instructions. Add additional test to make sure we correctly drop metadata from some instructions, while retaining it for others.

[fhahn]

llvm/tools/bugpoint-passes/TestPasses.cpp

178

I've slightly changed the test pass, to additionally require the operand to be an fadd instruction, to avoid the call being the only remaining instruction.

llvm/tools/bugpoint/CrashDebugger.cpp

852

Yes, we should retain metadata on all instructions in Insts/Instructions! This seems to be consistent with other ListReducers.

[reames]

LGTM