merge: refactor to reduce variable scope

These changes should not affect the behaviour of the code.

 * browser.c
 * buffy.c
 * mh.c
 * mutt/rfc2047.c
 * ncrypt/crypt_gpgme.c
 * newsrc.c
 * nntp.c
 * pager.c
 * parse.c
 * pattern.c
 * pgppubring.c
 * pop.c
 * pop_lib.c
 * postpone.c
 * query.c
 * recvattach.c
 * recvcmd.c
 * remailer.c
 * rfc1524.c
 * rfc2231.c
 * rfc3676.c
 * safe_asprintf.c
 * send.c
 * sendlib.c
 * sidebar.c
 * smtp.c
 * url.c
 * version.c