>This uses a static variable to have it persist between both the compare function calls that qsort makes and the main call which (potentially) changes its value to be 1 instead of 0

The only misleading thing here is that ‘static’ is monospaced in the article (this can’t be seen on HN). Other than that, ‘static variable’ can plausibly refer to an object with a static storage duration, which is what the C standard would call it.

>moving the variable from the stack to the "global data" which is generally heap-allocated as the program loads

It is not heap-allocated because you can’t free() it. Non-zero static data is not even anonymously mapped, it is file-backed with copy-on-write.