The NetBSD-current/i386 build is working again. The following commits were made between the last failed build and the successful build:
2018.05.19.18.14.36 christos src/external/bsd/byacc/dist/btyaccpar.skel,v 1.6 2018.05.19.18.14.51 christos src/external/bsd/byacc/dist/btyaccpar.c,v 1.6 2018.05.19.18.18.16 jakllsch src/sys/arch/i386/stand/mbr/gpt.S,v 1.2 2018.05.19.18.19.37 jakllsch src/sys/arch/i386/stand/mbr/gpt.S,v 1.3 Log files can be found at: http://releng.NetBSD.org/b5reports/i386/commits-2018.05.html#2018.05.19.18.19.37