Fix build with glib2 2.67.3+

[wenottingham]

glib headers should not be included with 'extern "C"'.

Change in glib that caused this: https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1715

Discussion of whether to work around it in glib: https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1935. This was rejected, the suggestion there was to fix it in the including programs.

It may be possible for an expert in the header inclusion hierarchy to make a more targeted fix - I just kept editing files until it built.

Build tested on Fedora rawhide, smoke tested by starting the program with a new account from scratch.

[jralls]

Thanks! I didn't even see this one coming.

BTW it's not possible to do a more targeted fix because glib won't let you include most internal headers from outside. You have to import glib.h. There are a few exceptions that add special features like glib/gprintf.h and glib/gi18n.h but neither of those has anything to do with this.

One other thing: It's better to put #include <glib.h> before the extern "C" block to override includes inside other headers declared extern "C".

[christopherlam]

Shouldnt this go to maint?

[jralls]

Yeah, the new glib will leak into something--likely MinGW64--before 5.0 gets released.

[wenottingham]

It's already in Fedora rawhide (which is how I ran across it.)

[jralls]

Does that mean that the next Fedora release will include it along with a recent GnuCash release (4.4 or 4.5 I suppose)? If so, why did you branch on master instead of maint?

[wenottingham]

Because I goofed up the branch, no other reason. Would you like another PR, or is that merge something you can do?

[jralls]

Easier for me to do it.