dbghelp: Now that we can keep ELF sections around, don't copy the loclist section, just don't unmap it.

dbghelp: Keep the file map around for every PE module, so that we can access image whenever we like to.

dbghelp: Extend the ELF image management to PE modules so we get a rather uniform interface to image manipulation.

Unfortunately there are plenty of other places left. Perhaps we should
consider creating our own window when the context becomes invalid and making
the context current on that instead.