selftests/bpf: make sure build-id is on

--build-id may not be a default linker config.
Make sure it's used when linking urandom_read test program.
Otherwise test_stacktrace_build_id[_nmi] tests will be failling.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/Makefile

@@ -19,7 +19,7 @@ all: $(TEST_CUSTOM_PROGS)
 $(TEST_CUSTOM_PROGS): urandom_read
 
 urandom_read: urandom_read.c
-	$(CC) -o $(TEST_CUSTOM_PROGS) -static $<
+	$(CC) -o $(TEST_CUSTOM_PROGS) -static $< -Wl,--build-id
 
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \