dovecot: Update to version 2.4.2

[essandess]

This PR makes several changes that adapt to the new 2.4 release.

My local build is currently failing with openssl linking errors:

…
:info:build       _openssl_iostream_alpn_select in iostream-openssl-context.o
:info:build ld: symbol(s) not found for architecture x86_64

Description

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS x.y
Xcode x.y / Command Line Tools x.y.z

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL in commit message?
• checked your Portfile with port lint?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?

[macportsbot]

Notifying maintainers:
@jdberry for port dovecot.

[essandess]

On v2.4.2, build fails with error:

:info:build Making all in lib-regex
:info:build make[3]: Entering directory `/opt/local/var/macports/build/dovecot-f6decbdd/work/dovecot-2.4.2/src/lib-regex'
:info:build make[3]: *** No rule to make target `-L/opt/local/lib', needed by `test-regex'.  Stop.

[essandess]

The cause of this is that the Makefile ./src/lib-regex/Makefile incorrectly includes the library path option -L/opt/local/lib as a library dependency:

LIBICU_LIBS = -L/opt/local/lib -licui18n -licuuc
LIBOBJS = 
LIBPCRE_CFLAGS = 
LIBPCRE_LIBS = -L/opt/local/lib -lpcre2-32
LIBS = 
LIBSODIUM_CFLAGS = 
LIBSODIUM_LIBS = -L/opt/local/lib -lsodium