Replace `enclose_io_memfs.c` in `make_enclose_io_memfs` with `INCBIN`

[ronaldtse]

This code inlines a SquashFS image in an array in a .c file which is hugely slow and inefficient:

https://github.com/metanorma/ruby-packer/blob/0d12afaafefa6ca4dfac4a3f8ced143bf1214205/lib/compiler.rb#L677-L690

We can directly link this image using mechanisms described here:

• https://developers.redhat.com/blog/2019/07/05/how-to-store-large-amounts-of-data-in-a-program
• The incbin macro can be used here for simplicity: https://github.com/graphitemaster/incbin

Original problems described in #4.

Originally posted by @ronaldtse in https://github.com/metanorma/ruby-packer/issues/16#issuecomment-845274950