Reduce scope of variables

• libwget/bar.c: Likewise
• libwget/console.c: Likewise
• libwget/encoding.c: Likewise
• libwget/hashmap.c: Likewise
• libwget/io.c: Likewise
• libwget/md5.c: Likewise
• libwget/netrc.c: Likewise
• libwget/ssl_gnutls.c: Likewise
• libwget/xml.c: Likewise
• src/job.c: Likewise
• src/plugin.c: Likewise
• libwget/hashfile.c: Include local private.h
• src/host.c: Remove unused find_free_job_context struct

Found by: cppcheck