Continuing effort to fix compiler warnings in benchmarks.

Set of small patches that resolve some of the outstanding compiler
warnings found when compiling the benchmarks.  Not all warnings are
fixed by this patch.

ChangeLog:

	* src/cubic/basicmath_small.c (main): Remove unused variables.
	* src/dtoa/dtoa.c (strtod): Remove unused variables.
	* src/edn/edn.c (codebook): Comment out tmpMask, given that the
	use of tmpMask is also commented out.
	* src/expint/expint.c (expint): Add brackets following the advice
	from gcc warnings.
	* src/fasta/fasta.c (random_fasta): Cast buf to void in order to
	silence a compiler warning.
	* src/fft/fft1.c (benchmark): Cast chkerr to void in order to
	silence a compier warning.
	* src/frac/frac.c (frac): Return a value from the bottom of the
	function to silence compiler warning.