Building gentoo-sources with genkernel starting with 4.15.0 always fails with this error:

*/bin/sh: line 1:  9599 Segmentation fault      ./tools/objtool/objtool orc generate --no-fp "fs/fat/.tmp_misc.o"

invoking genkernel with

nice -n 19 genkernel --oldconfig --firmware --disklabel --luks --makeopts=-j9 --install all

I suspected this to be a either a hardware or data corruption problem at first but, so I tried both 4.15.0 and 4.15.1 on two different machines. The result was the same, thus it doesn't look like a hardware / data corruption issue.
4.14.x and earlier kernels would build fine.
I am attaching my kernel config file, just in case it is relevant.