Extract gz compressed rcore files

Add support to extract gz compressed rich core files
This if-else-block is a bit hard to grok - especially that final else with length of 10 -> ".rcore.lzo".
Unless I'm mistaken the idea is to use path prior to suffix as destination directory.
Which could be done without multiple if-statements via something like:

output_dir = strndup(input_fn, suffix - input_fn);