spin_loop

spin_loop is used at run time in 33 crates. It is a direct run-time dependency in 5 crates.

Depender (with downloads and own rev deps)			spin_loop version
330	14	ach-util		^0.1
170	4	ach-cell		^0.1
150	3	ach-option		^0.1
130	1	ach-linked		^0.1
	2	ach-once		^0.1