Add memchecks for ELF loading.

Helps in games that use modules.
Upgrade symbolmaps with module address info.

This fixes some issues with jit replacement only if you had a map laying
around.
Ignore when a proxied block points to erased mem.

Happens for example when a new module is loaded, sometimes.
Merge pull request #6014 from unknownbrackets/debugger

Skip an error, add memchecks, upgrade old symbol maps