I thought it was fallout from my aarch64-clang patching. I dived in x265 git and supposedly there was fix, partially applicable to our patched x265.

Can anyone test on aarch64  gcc - I tested with termux/clang and it patches and builds ....

full git clone was done this way

git clone https://bitbucket.org/multicoreware/x265_git/

then I looked for specific commit

 git checkout -b aarch64 0b75c44c10e605fe9e9ebed58f04a46271131827

and extracted single commit

 git format-patch 931178347b3f73e40798fd5180209654536bbaa5

and then removed last part because this file was already changed between that we have and git at that point.

Commit was found by looking at this bugreport

may be we can test recent x265 git, too ...