llvm-dwarfdump: Report errors when failing to parse loclist/debug_loc entries

This probably isn't ideal - the error was being printed specifically
inline with the dumping that was more legible - but then the error
wasn't reported to stderr and didn't produce a non-zero exit code.

Probably the error message could be improved by adding more context now
that it isn't printed in-situ of the DIE dumping as much.