Make BTF generation reproducible

https://bugzilla.opensuse.org/show_bug.cgi?id=1230414

Index: linux-6.6/scripts/pahole-flags.sh
===================================================================
--- linux-6.6.orig/scripts/pahole-flags.sh
+++ linux-6.6/scripts/pahole-flags.sh
@@ -17,7 +17,7 @@ if [ "${pahole_ver}" -ge "121" ]; then
 	extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
 fi
 if [ "${pahole_ver}" -ge "122" ]; then
-	extra_paholeopt="${extra_paholeopt} -j"
+	extra_paholeopt="${extra_paholeopt} -j1"
 fi
 if [ "${pahole_ver}" -ge "124" ]; then
 	# see PAHOLE_HAS_LANG_EXCLUDE