vmtests: check in vmlinux.h and use it for non-latest builds

Manually generate vmlinux.h based on latest.config to be used for non-latest
selftest build. This will keep bpftool and newest selftests builds succeeding,
while at runtime blacklist will skip them.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

travis-ci/vmtest/build_selftests.sh

@@ -11,13 +11,20 @@ if [ -f "${PREPARE_SELFTESTS_SCRIPT}" ]; then
 	(cd "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" && ${PREPARE_SELFTESTS_SCRIPT})
 fi
 
+if [[ "${KERNEL}" = 'LATEST' ]]; then
+	VMLINUX_H=
+else
+	VMLINUX_H=${VMTEST_ROOT}/vmlinux.h
+fi
+
 make \
 	CLANG=clang-${LLVM_VER} \
 	LLC=llc-${LLVM_VER} \
 	LLVM_STRIP=llvm-strip-${LLVM_VER} \
 	VMLINUX_BTF="${VMLINUX_BTF}" \
+	VMLINUX_H=${VMLINUX_H} \
 	-C "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
-	-j $((4*$(nproc)))
+	-j $((2*$(nproc)))
 mkdir ${LIBBPF_PATH}/selftests
 cp -R "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
 	${LIBBPF_PATH}/selftests