adding gawk test case for sprintf formatting of Inf and NaN

[Andrew J. Schorr]

Attached is a proposed patch to gawk's test/Makefile.am and two new files
to supply the test (test/notfinite.awk and test/notfinite.OK).

If everything is working properly, "gawk -f notfinite.awk" should
not produce any output on stdout.  But with --lint, it should produce
a bunch of warnings about values being out of range.

Regards,
Andy

notfinite.awk
Description: Text document

notfinite.OK
Description: Text document

notfinite.patch
Description: Text document