luajit2: update to 2026-07-31

luajit2: update to 2026-07-31

Also refresh 020-riscv64-support.patch from the current state of
openresty/luajit2#236. The previous snapshot defined
asm_tail_prep(ASMState *as), but since openresty/luajit2 commit
68354f44 the callers pass a second TraceNo argument, so the riscv64
build failed with:

  lj_asm.c:2559:5: error: too many arguments to function 'asm_tail_prep'

The refreshed patch carries the upstream adaptation and restores the
build. The other four patches apply unchanged.

Signed-off-by: Josef Schlehofer <redacted>