gnucash stable: Multiple changes pushed

[Christopher Lam]

Updated	 via  https://github.com/Gnucash/gnucash/commit/534bea74 (commit)
	 via  https://github.com/Gnucash/gnucash/commit/3c5a1801 (commit)
	from  https://github.com/Gnucash/gnucash/commit/7e5f5597 (commit)



commit 534bea748f556097c45695180d4adb71c359f9bf
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Sat Nov 29 07:57:14 2025 +0800

    [guid.cpp] Specialise guid<->32-byte string
    
    - string->guid has branch-lite unrollable loop, fallback to slow
      boost parser
    - guid->string uses lookup table
    - avoids creating several temporary heap-allocated std::strings

commit 3c5a1801e29ed824287e95fdca57084c965e757a
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Fri Nov 28 00:31:12 2025 +0800

    [guid.cpp] fix guid==nullptr comparison retvals
    
    - if guid_1 guid_2 are both null they should return int(0) or bool(true)



Summary of changes:
 libgnucash/engine/guid.cpp | 85 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 64 insertions(+), 21 deletions(-)