Just like was done for bpftool and selftests inec23eb7056
("tools/bpftool: Allow substituting custom vmlinux.h for the build") andca4db6389d
("selftests/bpf: Allow substituting custom vmlinux.h for selftests build"), allow to provide pre-generated vmlinux.h for runqslower build. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210303004010.653954-1-andrii@kernel.org