Move i486/pthread_spin_trylock.S to pthread_spin_trylock.S

Since glibc doesn't support i386 any more, we can move
i486/pthread_spin_trylock.S to pthread_spin_trylock.S

	* sysdeps/i386/i486/pthread_spin_trylock.S: Moved to ...
	* sysdeps/i386/pthread_spin_trylock.S: Here.
	* sysdeps/i386/i586/pthread_spin_trylock.S: Removed.
	* sysdeps/i386/i686/pthread_spin_trylock.S: Updated.