Rely on baze make variable `location` to find protobuf include paths. #105

Job	Run time
build_attest_all (buildconfigs/key_xor_test_app.sh)	2m 7s
build_attest_all (buildconfigs/oak_client_android_app.sh)	44m 17s
build_attest_all (buildconfigs/oak_containers_kernel.sh)	24m 34s
build_attest_all (buildconfigs/oak_containers_orchestrator.sh)	5m 16s
build_attest_all (buildconfigs/oak_containers_stage1.sh)	3m 29s
build_attest_all (buildconfigs/oak_containers_syslogd.sh)	4m 34s
build_attest_all (buildconfigs/oak_containers_agent.sh)	3m 16s
build_attest_all (buildconfigs/oak_containers_system_image.sh)	11m 15s
build_attest_all (buildconfigs/oak_echo_enclave_app.sh)	2m 9s
build_attest_all (buildconfigs/oak_echo_raw_enclave_app.sh)	2m 19s
build_attest_all (buildconfigs/oak_functions_enclave_app.sh)	2m 18s
build_attest_all (buildconfigs/oak_functions_insecure_enclave_app.sh)	2m 26s
build_attest_all (buildconfigs/oak_orchestrator.sh)	2m 6s
build_attest_all (buildconfigs/oak_restricted_kernel_simple_io_init_rd_wrapper_bin.sh)	2m 33s
build_attest_all (buildconfigs/stage0_bin.sh)	2m 34s
	1h 55m 13s

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