[REL_2_STABLE] License: register PostgreSQL components under their own notices

[tuhaihe]

Several files inherited from PostgreSQL carry a copyright notice and licence of their own, but LICENSE did not list them. Add entries, with the notices copied verbatim under licenses/:

• BSD-3: BSD libc code under University of California notices (getopt, getopt_long, mkdtemp, pgmkdirp, fls, bsearch_arg, sort_template.h), the KAME MD5 and SHA-1 code, and pgcrypto's crypt-des.c.
• BSD-2: the pgcrypto files copyright Marko Kreen.
• ISC: strlcat.c, inet_net_ntop.c and timingsafe_bcmp.c.
• MIT: pgcrypto's Blowfish (from PuTTY) and imath.
• PostgreSQL-style: pageinspect, pgrowlocks and pgstattuple files copyright Tatsuo Ishii and Satoshi Nagayasu.
• Public domain: pgcrypto's bcrypt code and five message catalogs.
• Other permissive notices: pgcrypto's Rijndael, the GEQO operators adopted from Genitor, erand48.c and the pg_dump archiver.
• fuzzystrmatch's dmetaphone.c, which carries both a notice placing the Text::DoubleMetaphone portions under the same terms as Perl and a PostgreSQL-style notice for the rest.

Also list src/include/regex under the regex entry, and register Greenplum's gp_hyperloglog (BSD-2). Exclude the four licence texts that RAT does not recognize.

Assisted-by: Claude Code

Fixes #ISSUE_Number

What does this PR do?

Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (fix or feature with breaking changes)
• Documentation update

Breaking Changes

Test Plan

• Unit tests added/updated
• Integration tests added/updated
• Passed make installcheck
• Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• Followed contribution guide
• Added/updated documentation
• Reviewed code for security implications
• This PR contains AI-assisted code generation
• Requested review from cloudberry committers

Additional Context

CI Skip Instructions

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[tuhaihe]

Several files inherited from PostgreSQL carry a copyright notice and licence of
their own that LICENSE did not list. This registers them, with each notice copied
verbatim under licenses/. It addresses findings from a releasecheck pass over
2.2.0-rc2, of the same kind as the tabulate gap raised on rc1.

Licence	Files
BSD-3	BSD libc code under UC notices (getopt.c, getopt_long.c, mkdtemp.c, pgmkdirp.c, fls.c, bsearch_arg.c, sort_template.h); KAME MD5/SHA-1 (src/common/md5*, sha1*); pgcrypto crypt-des.c
BSD-2	the 28 pgcrypto files copyright Marko Kreen
ISC	strlcat.c, src/port/inet_net_ntop.c (added to the existing entries), timingsafe_bcmp.c
MIT	pgcrypto Blowfish (from PuTTY) and imath
PostgreSQL-style	pageinspect / pgrowlocks / pgstattuple files by Tatsuo Ishii and Satoshi Nagayasu
Public domain	pgcrypto bcrypt (Solar Designer); five .po catalogs that declare themselves public domain
Other permissive	pgcrypto Rijndael (Brian Gladman), GEQO operators adopted from Genitor (Darrell Whitley), erand48.c, the pg_dump archiver (Philip Warner)
Perl + PostgreSQL-style	contrib/fuzzystrmatch/dmetaphone.c, which carries both notices

Also:

• src/include/regex is added to the existing regex entry, which listed only src/backend/regex.
• Greenplum's gp_hyperloglog (BSD-2) is registered in the Greenplum section.
• pom.xml excludes the four licence texts RAT does not recognize (geqo, rijndael, erand48, pg_dump).

[leborchuk]

LGTM