NetBSD 9.2 Alpha: error in conversion of int64_t to long double

["Nelson H. F. Beebe" <beebe%math.utah.edu@localhost>]

The small Web site 

	http://www.math.utah.edu/~beebe/netbsd-alpha/

contains these new files:

	-rw-rw-r-- 1 1046 Sep 14 14:08 netbsd-alpha-bug001.c
	-r--r--r-- 1  196 Sep 14 14:12 netbsd-alpha-bug001.lst-Linux-alpha
	-r--r--r-- 1  196 Sep 14 14:11 netbsd-alpha-bug001.lst-Linux-x86_64
	-r--r--r-- 1  192 Sep 14 14:09 netbsd-alpha-bug001.lst-NetBSD-alpha

They demonstrate incorrect conversion of int64_t to long double on
NetBSD 9.2 Alpha, and are modeled on test software for cube roots, but
reduced to minimal code to exhibit the conversion error.

The C compiler versions are gcc 10.2.1 on Debian, 10.3.0 on NetBSD,
and 4.8.5 on the CentOS 7 system that produced the *.lst-Linux-x86_64
output.

On NetBSD Alpha, long double is a synonym for double, both a 64-bit
IEEE 754 binary type.

By contrast, on Debian 11 Alpha, long double corresponds to the
128-bit IEEE 754 binary type, and that system exhibits expected output
in the extensive environmental tests in features-1.2.3, available at

	http://www.math.utah.edu/pub/features/

A more probing version, features-1.2.4, is in development, and may
appear in the next few weeks at that site.

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