This change will fix the BINDER_SET_MAX_THREADS ioctl to use __u32
instead of size_t for setting the max threads. Thus using the same
handler for 32 and 64bit kernels.
This value is stored internally in struct binder_proc and set to 15
on open_binder() in the libbinder API(thus no need for a 64bit size_t
on 64bit platforms).