Fix typos and licence in newlib benchmarks.

	* src/newlib-exp/ef_exp.c: Move original licence to the top of the
	    file. Change e_exp to ef_exp.
	* src/newlib-log/ef_log.c: Move original licence to the top of the
	    file. Fix typo.
	* src/newlib-sqrt/ef_sqrt.c: Move original licence to the top of the
	    file.