Requested changes

- Split comparison ifs into two seperate ifs for both cog and cas
- Changed variable name for shdict cog from match to unmatch
- Added comment to "only set flag" branch in shdict store
- Removed some unesesary blank lines
- Moved forcefull alloc for shdict store and cas into a seperate function
- Removed unsued function "ngx_http_lua_ffi_shdict_get_conditonal"

Author: Miniwoffer