Regarding the conker issue it asserts when compiling with FORCE_DRC_C_BACKEND=1:

c:\Emulation\mess>gdb --batch --eval-command="set target-harset UTF-8" --eval-command="set demangle-style auto" --eval-command=run --eval-command=bt --return-child-result --args "c:\Emulation\mess\messd_nodrc.exe" n64 -cart "conker" -artpath c:\Emulation\mess\artwork -video none -nosound -nothrottle -nodebug -nomouse -window -seconds_to_run 4 -rompath "s:\_roms\mess;s:\_roms\mess_software" -hashpath "c:\Emulation\mess\hash"
[New Thread 9004.0x20c8]
CIC-NUS-6105 detected
warning: assert: src/emu/cpu/drcbeut.c:383: mapvar >= MAPVAR_M0 && mapvar < MAPVAR_END

Program received signal SIGTRAP, Trace/breakpoint trap.
0x7676280d in KERNELBASE!DeleteAce () from C:\Windows\syswow64\KernelBase.dll
#0 0x7676280d in KERNELBASE!DeleteAce () from C:\Windows\syswow64\KernelBase.dll
#1 0x01984670 in osd_break_into_debugger (message=0x9bd2c3c "assert: src/emu/cpu/drcbeut.c:383: mapvar >= MAPVAR_M0 && mapvar < MAPVAR_END") at src/osd/windows/winmisc.c:187
#2 0x01bfd9dd in emu_fatalerror::emu_fatalerror(char const*, ...) ()
#3 0x015576a5 in _ZNK17drc_map_variables9get_valueEPhj (this=0xfdc372c, codebase=0x150e9024 "\264Q\336\017,\220\016\025\001", mapvar=<unknown type>) at src/emu/cpu/drcbeut.c:383
#4 0x0154ec22 in _ZN7drcbe_c7executeERN3uml11code_handleE (this=0xfdc36dc, entry=0xfde46dc) at src/emu/cpu/drcbec.c:641
#5 0x01b00dd5 in drcuml_state::execute(uml::code_handle&) ()
#6 0x01344ba8 in _ZL17cpu_execute_mips3P17legacy_cpu_device (device=0x7f2cfdc) at src/emu/cpu/mips/mips3drc.c:541
#7 0x017a8035 in _ZN17legacy_cpu_device11execute_runEv (this=0x7f2cfdc) at src/emu/devcpu.c:260
#8 0x01d8ff8c in device_execute_interface::run() ()
#9 0x0162dd43 in _ZN16device_scheduler9timesliceEv (this=0x28f270) at src/emu/schedule.c:487
#10 0x0158bdf6 in _ZN15running_machine3runEb (this=0x28edb8, firstrun=True) at src/emu/machine.c:414
#11 0x015587dc in _Z12mame_executeR11emu_optionsR13osd_interface (options=0x28fb90, osd=0x28fe74) at src/emu/mame.c:176
#12 0x01794ba7 in _ZN12cli_frontend7executeEiPPc (this=0x28fe68, argc=19, argv=0x352ff8) at src/emu/clifront.c:246
#13 0x00fc967d in _Z9utf8_mainiPPc (argc=19, argv=0x352ff8) at src/osd/windows/winmain.c:482
#14 0x0198442e in wmain (argc=19, argv=0x351518) at src/osd/windows/main.c:88
#15 0x00401422 in __tmainCRTStartup () at ../mingw-w64-crt/crt/crtexe.c:282
#16 0x7699339a in KERNEL32!BaseCleanupAppcompatCacheSupport () from C:\Windows\syswow64\kernel32.dll
#17 0x7efde000 in ?? ()
#18 0x77ca9ef2 in ntdll!RtlpNtSetValueKey () from C:\Windows\system32\ntdll.dll
#19 0x7efde000 in ?? ()
#20 0x77ca9ec5 in ntdll!RtlpNtSetValueKey () from C:\Windows\system32\ntdll.dll
#21 0x00401550 in __tmainCRTStartup () at ../mingw-w64-crt/crt/crtexe.c:288
#22 0x00000000 in ?? ()