This test uses the same framework as the regcomp012 performance
tests and the test012 correctness tests, but different files
of test cases.

In fact, this test uses only one regexp:

	(a.*bcde|a.*cde|a.*de|a.*e)(a.*b|a.*c|a.*d|a.*e)\1

The test is run 3 times, each time doubling the length of the string
being compared to the regexp.  Rx takes a time that is quadratic in
the length of that string, Regex is exponential.

If you run
	
	./=compile ../../regex/regex.h  ../../=build/regex/regex.o
	./=doit ,gnu

four files are generated.  ",gnu-<n>" for <n> = 0,1,2 or 3 contains
the timing results for that test. ",gnu-plot" contains a summary
of the tests, usitable for plotting with gnuplot.  Try this sequence:

	% ./=compile ../../rx/inst-rxposix.h ../../=build/rx/librx.a
	% ./=doit ,rx
	% ./=compile ../../regex/regex.h  ../../=build/regex/regex.o
	% ./=doit ,gnu
	% gnuplot
	gnuplot> plot ",rx-plot" with linespoints, ",gnu-plot" with linespoints
	...
	gnuplot> quit

