Fixed complaining when Xresources field is blank
Fixed minor memory alloc problems for test

Hashmap test had some memory allocation problems in it that I missed
before, that has been fixed. This shouldn't really affect anyone who's
not building Putty with testing hashmap in mind.
Abstracted Xresources load away from hashmap

As a result, Xresources loading should now work even when building Putty
with legacy containers option set. Should also make loading logic more
durable.