Does not comile with postgres 18

[RekGRpth]

Commit ​https://github.com/postgres/postgres/commit/d4a43b283751b23d32bbfa1ecc2cad2d16e3dde9 converts libpgport's pqsignal() to a void function.

#9 371.9 postgis_module.c: In function '_PG_init':
#9 371.9 postgis_module.c:83:18: error: void value not ignored as it ought to be
#9 371.9    83 |   coreIntHandler = pqsignal(SIGINT, handleInterrupt);
#9 371.9       |                  ^
#9 371.9 make[1]: *** [<builtin>: postgis_module.o] Error 1
#9 371.9 make[1]: *** Waiting for unfinished jobs....
#9 372.2 make: *** [GNUmakefile:36: all] Error 1

[Laurenz Albe]

I'm hitting the same problem.

I think the right fix would be to get rid of coreIntHandler: _PG_fini() could simply be removed (it is never called from PostgreSQL), and handleInterrupt(int) can just skip calling the previous interrupt handler.

[Laurenz Albe]

The same applies to sfcgal/lwgeom_sfcgal.c and raster/rt_pg/rtpostgis.c.

[pramsey]

Done in #5841