reorder mutex struct fields to make room for pointers (upcoming robust mutexes)
reorder mutex struct fields to make room for pointers (upcoming robust mutexes)

the layout has been chosen so that pointer slots 3 and 4 fit between
the integer slots on 32-bit archs, and come after the integer slots on
64-bit archs.

chneukirchen/musl-chris2,davidlazar/musl,chardi/musl,rofl0r/musl-old,chardi/musl,rofl0r/musl-old,chardi/musl,chneukirchen/musl-chris2,davidlazar/musl