perf build: Always disable stack protection for BPF skeleton objects

When the clang toolchain has stack protection enabled, the bpf
skeletons build fails with:

error: A call to built-in function '__stack_chk_fail' is not supported.

Since stack-protector makes no sense for the BPF bits, just unconditionally
disable it.

See also similar case at 878625e1c7a10dfbb1fdaaaae2c4d2a58fbce627

Signed-off-by: Federico Pellegrin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ rearrange long lines ]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/Makefile.perf

···
 	$(Q)cp "$(VMLINUX_H)" $@
 endif
 
-$(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(OUTPUT)PERF-VERSION-FILE util/bpf_skel/perf_version.h $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT)
-	$(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf $(CLANG_OPTIONS) $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \
+$(SKEL_TMP_OUT)/%.bpf.o: $(OUTPUT)PERF-VERSION-FILE util/bpf_skel/perf_version.h | $(SKEL_TMP_OUT)
+$(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h
+	$(QUIET_CLANG)$(CLANG) -g -O2 -fno-stack-protector --target=bpf \
+	  $(CLANG_OPTIONS) $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \
 	  -include $(OUTPUT)PERF-VERSION-FILE -include util/bpf_skel/perf_version.h \
 	  -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@