configure.target: Use cpu_include_dir="config/cpu/sparc" for all sparc targets.

	* configure.target: Use cpu_include_dir="config/cpu/sparc" for all
	sparc targets.
	* config/cpu/sparc/atomicity.h: New file.
	* config/cpu/sparc/sparc32/atomicity.h: Removed.
	* config/cpu/sparc/sparc64/atomicity.h: Removed.

From-SVN: r56896