Fall back to disassembly in case typecast fails.

Since some time now, we construct minimal dwarf image debug infos
for release images if they contain frame unwind information, in order
to allow using that to unwind the stack in as many cases as possible.
As such, it's  entirely possible that such an image may be asked for
statement information regarding a function that isn't in fact compiled
with debugging. As such, we need to simply fall back to disassembly
rather than failing entirely. Fixes setting breakpoints in such
functions (i.e. anything in a release version of libstdc++).
Fix regression introduced in 6b308faf.

That commit switched to a single string column for representing
breakpoint locations, but neglected to update the case of a breakpoint
in a non-debug function to actually format the address as a string
appropriately, leading to those simply showing no data since then.