ci: make CI build log less verbose

Only keep stderr output in case of errors for kernel and selftests builds.
Having a multi-thousand-line output isn't useful and slows down Github
Actions' log view UI.

Also quiet down wget's "progress bar" output. While at the same time see some
totals from tar, just for the fun of it.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

travis-ci/vmtest/build_selftests.sh

@@ -30,7 +30,7 @@ make \
 	VMLINUX_BTF="${VMLINUX_BTF}" \
 	VMLINUX_H=${VMLINUX_H} \
 	-C "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
-	-j $((4*$(nproc)))
+	-j $((4*$(nproc))) >/dev/null
 mkdir ${LIBBPF_PATH}/selftests
 cp -R "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
 	${LIBBPF_PATH}/selftests

travis-ci/vmtest/checkout_latest_kernel.sh

@@ -32,7 +32,7 @@ if [ ! -d "${REPO_PATH}" ]; then
 	mkdir -p $(dirname "${REPO_PATH}")
 	cd $(dirname "${REPO_PATH}")
 	# attempt to fetch desired bpf-next repo snapshot
-	if wget ${SNAPSHOT_URL} && tar xf bpf-next-${LINUX_SHA}.tar.gz ; then
+	if wget -nv ${SNAPSHOT_URL} && tar xf bpf-next-${LINUX_SHA}.tar.gz --totals ; then
 		mv bpf-next-${LINUX_SHA} $(basename ${REPO_PATH})
 	else
 		# but fallback to git fetch approach if that fails

travis-ci/vmtest/prepare_selftests.sh

@@ -13,7 +13,7 @@ if [[ "${KERNEL}" = 'LATEST' ]]; then
 	travis_fold start build_kernel "Kernel build"
 
 	cp ${VMTEST_ROOT}/configs/latest.config .config
-	make -j $((4*$(nproc))) olddefconfig all
+	make -j $((4*$(nproc))) olddefconfig all >/dev/null
 
 	travis_fold end build_kernel
 fi