[PATCH 0/3] libm: Clean up gamma functions

[Keith Packard]

This  series  cleans   up  some  API  oddities   and  inaccuracies  in
errno/exception reporting  from the  various gamma  related functions.
With this series applied, newlib now  matches the POSIX spec (and glibc)
for  tgamma/lgamma  functions. I've  left  the  'gamma' functions  BSD
compatible (tgamma instead of lgamma) to avoid changing the API.

[PATCH 1/3] libm: Fix sign value returned from __ieee754_lgamma*_r(-0)

	Following the C spec, gamma(-0) should be -INFINITY rather than
	+INFINITY, so the *signgamp value in lgamma should be -1
	rather than +1 for this case.

[PATCH 2/3] libm: Remove __ieee754_gamma_r variants

	Back in 2002, a patch changed the various gamma functions so
	that the returned abs(gamma) instead of the ln of gamma. This
	left the _r variants in place, with their extra parameter to
	return the sign of the resulting value. This doesn't make any
	sense to me and looks like it was just a mistake. I've changed
	the __ieee754_gamma functions to apply the sign value locally
	and eliminated the gamma_r versions as those are no longer useful.

[PATCH 3/3] libm: Adjust errno/exception values for gamma/lgamma

	There's a pretty detailed discussion in the commit message
	here, the short version is that tgamma and lgamma are
	specified with different errno/exception behaviour for
	one class of inputs (negative integers).