Recent vlc-3.0.0-r3 fails to build on arm, due to simple_neon.h not be found (whatever that should be) - this was fixed in vlc-3.0.1 appareantly, I just made a test compile and can now get past the breakage in audio_filter/channel_mixer/simple.c which was due to the headers not been found.
Closing as invalid, the build got borked a bit later on because of a missing asm.S file. But I build the live ebuild 3.0.9999 (895fe79411b74c551d2b0c56257818841678b2c4) with success, and I consider this being fixed in git, it will get washed down by revbumps anyway. It might be possible to identify the commits solving this, but the rpi is too slow to test every single commit for failure with the solution being on the horizon.