Bug 1225858

GCC 14 newly by default treats as errors a number of situations which
before were only warnings.  For more information see
https://gcc.gnu.org/gcc-14/porting_to.html and meta bug #1220571.

Because of this, package libsmi fails to compile.  This can be seen online
at:
https://build.opensuse.org/package/live_build_log/openSUSE:Factory:Staging:Gcc7/libsmi/standard/x86_64

It can be reproduced locally with command: osc build --clean
--alternative-project home:rguenther:nextgcc

See especially
https://gitlab.com/fweimer-rh/fedora-modernc/-/tree/main/pkg/l?ref_type=heads
which has some patches for improved C99 compliance but because of some
Bison generated type mismatch they decided to solve this with compiler
flags.

Corresponding Gentoo bug: https://bugs.gentoo.org/869149


The (first) error (that halts the build) is:

[   18s] parser-sming.y: In function 'checkDate':
[   18s] parser-sming.y:255:19: error: implicit declaration of function 'timegm'; did you mean 'time'? [-Wimplicit-function-declaration]
[   18s]   255 |         anytime = timegm(&tm);
[   18s]       |                   ^~~~~~
[   18s]       |                   time