CMAKE Parameters for armv6+vfp build

I'm trying to build tf-lite with XNNPACK enabled for armv6+vfp architecture(RasPi 1/Zero/Zero W), which fails due to cmake adding `-march=armv8.2-a+dotprod -mfpu=neon-fp-armv8` to CLFAGS by checks in the CMakeLists.txt . However as I have absolutely no idea of the internals of how tf-lite uses XNNPACK, I started to look at xnnpack itself.

After examining the CMakeLists.txt, I was unable to figure out the flags to be passed to cmake that'll allow xnnpack to be built for armv6+vfp.

How is XNNPACK to be built for this architecture using cmake, given that support for Raspberry Pi Zero W is clearly stated in the README?