In /usr/include/asm/unistd_64.h, there is:
#define _ASM_X86_UNISTD_64_H 1
Yes, this was my mistake. Upstream removed the target to generate all headers and I incorrectly recreated the script.
https://koji.fedoraproject.org/koji/taskinfo?taskID=36328729 should have all the appropriate headers. If it doesn't look right, let me know and I'll fix it up.
I built the git7 kernel with the updated headers in the buildroot and it looked to be okay (it was failing with the bad headers previously)
glibc builds are working now too