posix_spawnattr_init() no longer pre-fills attr->stacksize and
attr->priority (it leaves them zero, as memset already does). When a
caller does not set them, the binary loader supplies them from the
loaded ELF (binp->stacksize / binp->priority, parsed from the nx_*
symbols), and nxtask_spawn_exec() falls back to the parent priority and
CONFIG_POSIX_SPAWN_DEFAULT_STACKSIZE for the posix_spawn() function-task
path.
This lets an application's stack size and priority embedded as ELF
symbols actually drive the spawned task, instead of being overridden by
the spawnattr defaults.
Signed-off-by: anjiahao <anjiahao@xiaomi.com>