Error in 5.15.86 ct_event

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Test member nf_ct_event_notifier.ct_event net/netfilter/nf_conntrack_ecache.h  undeclared
egrep: warning: egrep is obsolescent; using grep -E
Error: unexpected error from compiler
make -s -B -C /mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/linux-5.15.86 M=/mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2/cc-test-build modules
/mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2/cc-test-build/test.c:4:41: error: invalid use of undefined type 'struct nf_ct_event_notifier'
    4 | typeof(((struct nf_ct_event_notifier*)0)->ct_event) test;
      |                                         ^~
make[5]: *** [scripts/Makefile.build:289: /mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2/cc-test-build/test.o] Error 1
make[4]: *** [Makefile:1903: /mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2/cc-test-build] Error 2

make[3]: *** [Makefile:30: compat_def.h] Error 3
make[3]: Leaving directory '/mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2'
make[2]: *** [Makefile:121: /mnt/zeus/hdd/sources/openwrt/sources/snapshot/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/linux-mvebu_cortexa9/ipt-netflow-40fefb2/.built] Error 2
make[2]: Leaving directory '/mnt/zeus/hdd/sources/openwrt/sources/snapshot/package/network/ipt-netflow'
time: package/network/ipt-netflow/compile#14.33#7.78#21.41
    ERROR: package/network/ipt-netflow failed to build.
make[1]: *** [package/Makefile:116: package/network/ipt-netflow/compile] Error 1
make[1]: Leaving directory '/mnt/zeus/hdd/sources/openwrt/sources/snapshot'
make: *** [/mnt/zeus/hdd/sources/openwrt/sources/snapshot/include/toplevel.mk:231: package/network/ipt-netflow/compile] Fehler 2