dovecot: update to 2.3.19.1, sieve to 0.5.19 completely breaks build, APNS

[essandess (Steve Smith)]

Commit ​https://github.com/macports/macports-ports/commit/301eda8b32a1dc39639a82b71ff0537850462435 makes extensive change to the build process that breaks the build for push notifications, downloads files during the build, introduces patch files that are unnecessary with autoconf, and makes other breaking changes. E.g.,

:info:build Undefined symbols for architecture x86_64:
:info:build   "_cmd_x_apple_push_service", referenced from:
:info:build Undefined symbols for architecture x86_64:
:info:build   "_cmd_x_apple_push_service", referenced from:
:info:build       _imap_ext_commands in imap-commands.o
:info:build       _imap_ext_commands in imap-commands.o
:info:build ld: symbol(s) not found for architecture x86_64
:info:build ld: symbol(s) not found for architecture x86_64
:info:build clang: error: linker command failed with exit code 1 (use -v to see invocation)
:info:build clang: error: linker command failed with exit code 1 (use -v to see invocation)
:info:build make[3]: *** [imap] Error 1
:info:build make[3]: *** Waiting for unfinished jobs....
:info:build make[3]: *** [test-imap-client-hibernate] Error 1
:info:build make[3]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_mail_dovecot/dovecot/work/dovecot-2.3.19.1/src/imap'
:info:build make[2]: *** [all-recursive] Error 1
:info:build make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_mail_dovecot/dovecot/work/dovecot-2.3.19.1/src'
:info:build make[1]: *** [all-recursive] Error 1

I've issued a PR that attempts to undo these changes while keeping other non-breaking changes made in ​https://github.com/macports/macports-ports/commit/301eda8b32a1dc39639a82b71ff0537850462435