lib-sieve: plugins: include: ext-include-binary - Properly check whether binary dependency block load succeeded.

Otherwise, a segfault may occur on a corrupt binary.

The sieve_binary_block_index/get() functions return NULL when the block index is
invalid somehow. This was not handled by the dumper, thereby causing a crash.

Problem reported by scan-build.

lib-sieve: plugins: imap4flags: test-hasflag - Fix segfault occurring for command without arguments.

This commit simplifies the help-string definitions and makes them more
consistent with the upstream configuration of the dovecot/core project.

Drop the inline definition of the TEST_WITH macro in favor of using a
verbatim copy of the file that contains the macro from the dovecot/core
project. This allows easier tracking of changes to the macro that happen
upstream.

Copied verbatim from dovecot/core project.

Copied verbatim from dovecot/core project.

This is a corner case that doesn't happen in practice, but it can be created in
the test suite.

This reverts commit ffbcd3bf.

This applies to the vacation and notify actions, which produce new free-form
outgoing messages.

lib-sieve: enotify extension: mailto: Enforce subject header limit in Unicode codepoints rather than bytes.