Fix last commit (35e6859)

* src/rfc822parse.c (parse_field): Replace break by goto.

Brown paper bag bug: Changing an IF to a WHILE inside another loop
requires to fix the inner break.

(backported from gnupg 2.1
commit 9433661419043431a6cfc7d84c8450e0b2f6c353)

• Reported-by: Hanno Böck
• Signed-off-by: Werner Koch <wk@gnupg.org>