The NetBSD-current/i386 build is working again. The following commits were made between the last failed build and the successful build:
2018.11.19.10.05.09 kre src/sys/arch/amd64/include/frame.h,v 1.19 2018.11.19.10.05.09 kre src/sys/arch/i386/include/frame.h,v 1.38 2018.11.19.10.05.09 kre src/sys/arch/xen/x86/hypervisor_machdep.c,v 1.33 2018.11.19.10.14.40 maya src/sys/dev/audio_dai.h,v 1.4 2018.11.19.10.45.47 jmcneill src/sys/arch/aarch64/aarch64/bus_space.c,v 1.7 2018.11.19.10.45.47 jmcneill src/sys/arch/arm/acpi/acpipchb.c,v 1.7 2018.11.19.10.45.47 jmcneill src/sys/arch/arm/arm32/armv7_generic_space.c,v 1.10 2018.11.19.10.45.47 jmcneill src/sys/arch/arm/include/bus_defs.h,v 1.13 2018.11.19.10.48.59 maya src/sys/external/bsd/drm2/include/linux/regulator/consumer.h,v 1.5 2018.11.19.11.08.16 jmcneill src/sys/arch/arm/fdt/pcihost_fdt.c,v 1.6 Log files can be found at: http://releng.NetBSD.org/b5reports/i386/commits-2018.11.html#2018.11.19.11.08.16