gnucash maint: Multiple changes pushed

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/81b9a022 (commit)
	 via  https://github.com/Gnucash/gnucash/commit/67e8c317 (commit)
	from  https://github.com/Gnucash/gnucash/commit/25181a6c (commit)



commit 81b9a022353a32ad1f913a91ad999f93b1d09bd7
Author: John Ralls <jralls at ceridwen.us>
Date:   Tue Mar 1 12:19:44 2022 -0800

    Bug 798458 - Build failure with gcc 12
    
    Refactor try_gz_open to return a std::pair<FILE*, thread>. That removes
    the need for the threads hash-table and wait_for_gzip().
    
    The cause of the gcc12 error was that we were using the thread's pipe's
    FILE* as the key to the hash-table and had to close it before calling
    wait_for_gzip(file) to remove the thread from the hash-table. gcc12
    considers that a use-after-free. It happens to be wrong, but removing the
    need for it results in a cleaner implementation as well as silencing the
    warning.

commit 67e8c317dab481577d805601e056c74382880b57
Author: John Ralls <jralls at ceridwen.us>
Date:   Tue Mar 1 12:08:59 2022 -0800

    [xml backend] Extract functions to make gz_trhead_func more readable.



Summary of changes:
 libgnucash/backend/xml/io-gncxml-v2.cpp | 333 +++++++++++++++-----------------
 1 file changed, 161 insertions(+), 172 deletions(-)