Interestingly enough this breaks my rpmbuild (both rpmbuild and mock).
(mostly with a modified f35 spec file):
cc -Isubprojects/libvhost-user/libvhost-user.a.p -Isubprojects/libvhost-user
-I../subprojects/libvhost-user -fdiagnostics-color=auto -pipe -Wall
-Winvalid-pch -std=gnu11 -O2 -g -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -m64
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes
-Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes
-fno-strict-aliasing -fno-common -fwrapv -O2 -fexceptions -g
-grecord-gcc-switches -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
-Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
-fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64
-march=zEC12 -mtune=z13 -fasynchronous-unwind-tables -fstack-clash-protection
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs
-Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2
-Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi
-fstack-protector-strong -DSTAP_SDT_V2 -fPIE -pthread -D_GNU_SOURCE -MD -MQ
subprojects/libvhost-user/libvhost-user.a.p/libvhost-user.c.o -MF
subprojects/libvhost-user/libvhost-user.a.p/libvhost-user.c.o.d -o
subprojects/libvhost-user/libvhost-user.a.p/libvhost-user.c.o -c
../subprojects/libvhost-user/libvhost-user.c
../subprojects/libvhost-user/libvhost-user.c:43:10: fatal error:
include/atomic.h: No such file or directory
43 | #include "include/atomic.h"
| ^~~~~~~~~~~~~~~~~~
compilation terminated.