Update config-host.h

[zxalexis]

Fix build compatibility with GCC 15.2+ which defaults to -std=c23

[markpizz]

Does the makefile build on that host?
If so, the problem is in the cmake setup which is forcing a new C dialect on a long functioning codebase.

[markpizz]

Like I said above, the necessary fix to solve your problem is in the cmake logic.

The makefile builds just fine:

*** pdp11 Simulator being built with:
*** - compiler optimizations and no debugging support. GCC Version: 15.2.1.
*** - dynamic networking support using Linux provided libpcap components.
*** - Local LAN packet transports: PCAP TAP NAT(SLiRP)
*** - video capabilities provided by libSDL2 (Simple Directmedia Layer).
*** - Per simulator tests will be run.
***
*** git commit id is 4d38373206cd7c0ce8b94f5e16bd4429cb96430f.
*** git commit time is 2025-10-12T07:58:51+0200.
***
gcc -std=gnu99 -U__STRICT_ANSI__  -O2 -DNDEBUG=1 -finline-functions -fgcse-after-reload -fpredictive-commoning -fipa-cp-clone -fno-unsafe-loop-optimizations -fno-strict-overflow -DSIM_GIT_COMMIT_ID=4d38373206cd7c0ce8b94f5e16bd4429cb96430f -DSIM_GIT_COMMIT_TIME=2025-10-12T07:58:51+0200  -DSIM_COMPILER="GCC Version: 15.2.1" -DSIM_BUILD_TOOL=simh-makefile -I . -Werror -D_GNU_SOURCE -DHAVE_PCRE_H -DHAVE_SEMAPHORE -DHAVE_SYS_IOCTL -DHAVE_LINUX_CDROM -DSIM_HAVE_DLOPEN=so -DHAVE_EDITLINE -DHAVE_UTIME -DHAVE_LIBPNG -DHAVE_ZLIB -DHAVE_GLOB -DHAVE_SHM_OPEN  ./PDP11/pdp11_fp.c ./PDP11/pdp11_cpu.c ./PDP11/pdp11_dz.c ./PDP11/pdp11_cis.c ./PDP11/pdp11_lp.c ./PDP11/pdp11_rk.c ./PDP11/pdp11_rl.c ./PDP11/pdp11_rp.c ./PDP11/pdp11_rx.c ./PDP11/pdp11_stddev.c ./PDP11/pdp11_sys.c ./PDP11/pdp11_tc.c ./PDP11/pdp11_tm.c ./PDP11/pdp11_ts.c ./PDP11/pdp11_io.c ./PDP11/pdp11_rq.c ./PDP11/pdp11_tq.c ./PDP11/pdp11_pclk.c ./PDP11/pdp11_ry.c ./PDP11/pdp11_pt.c ./PDP11/pdp11_hk.c ./PDP11/pdp11_xq.c ./PDP11/pdp11_xu.c ./PDP11/pdp11_vh.c ./PDP11/pdp11_rh.c ./PDP11/pdp11_tu.c ./PDP11/pdp11_cpumod.c ./PDP11/pdp11_cr.c ./PDP11/pdp11_rf.c ./PDP11/pdp11_dl.c ./PDP11/pdp11_ta.c ./PDP11/pdp11_rc.c ./PDP11/pdp11_kg.c ./PDP11/pdp11_ke.c ./PDP11/pdp11_dc.c ./PDP11/pdp11_dmc.c ./PDP11/pdp11_kmc.c ./PDP11/pdp11_dup.c ./PDP11/pdp11_rs.c ./PDP11/pdp11_vt.c ./PDP11/pdp11_td.c ./PDP11/pdp11_io_lib.c ./PDP11/pdp11_rom.c ./PDP11/pdp11_ch.c ./PDP11/pdp11_dh.c ./PDP11/pdp11_ng.c ./PDP11/pdp11_daz.c ./PDP11/pdp11_tv.c ./PDP11/pdp11_mb.c ./PDP11/pdp11_rr.c ./display/display.c ./display/sim_ws.c ./display/ng.c ./display/vt11.c ./scp.c ./sim_console.c ./sim_fio.c ./sim_timer.c ./sim_sock.c ./sim_tmxr.c ./sim_ether.c ./sim_tape.c ./sim_disk.c ./sim_serial.c ./sim_video.c ./sim_imd.c ./sim_card.c -DVM_PDP11 -I ./PDP11 -DHAVE_PCAP_NETWORK -I/usr/include/ -DBPF_CONST_STRING -DUSE_SHARED -DHAVE_TAP_NETWORK -Islirp -Islirp_glue -Islirp_glue/qemu -DHAVE_SLIRP_NETWORK -DUSE_SIMH_SLIRP_DEBUG slirp/*.c slirp_glue/*.c -DUSE_DISPLAY -DHAVE_LIBSDL -DUSE_SIM_VIDEO `sdl2-config --cflags` `sdl2-config --libs` -DUSE_READER_THREAD -DSIM_ASYNCH_IO -o BIN/pdp11 -lm -lrt -lpthread -lpcre -ldl -ledit -ltermcap -lpng -lz
BIN/pdp11 RegisterSanityCheck  </dev/null
 Running internal register sanity checks on PDP-11 simulator.
*** Good Registers in PDP-11 simulator.