Fix: return NaN under appropriate conditions

This propagates any signals which happen to be on the `NaN`, mimicking
the behavior of OpenLibm (though, I suspect no one depends on
signaling `NaN`s being propagated through `logabsgamma`).

Author: andrewjradcliffe

src/e_lgamma_r.jl

@@ -94,7 +94,7 @@ function _logabsgamma(x::Float64)
     #= purge off +-inf, NaN, +-0, tiny and negative arguments =#
     signgam = 1
     ix = hx & 0x7fffffff
-    ix ≥ 0x7ff00000 && return Inf, signgam
+    ix ≥ 0x7ff00000 && return x * x, signgam
     ix | lx == 0x00000000 && return Inf, signgam
     if ix < 0x3b900000 #= |x|<2**-70, return -log(|x|) =#
         if hx < Int32(0)

src/e_lgammaf_r.jl

@@ -22,7 +22,7 @@ function _logabsgamma(x::Float32)
     #= purge off +-inf, NaN, +-0, tiny and negative arguments =#
     signgam = 1
     ix = hx & 0x7fffffff
-    ix ≥ 0x7f800000 && return Inf32, signgam
+    ix ≥ 0x7f800000 && return x * x, signgam
     ix == 0x00000000 && return Inf32, signgam
     if ix < 0x35000000 #= |x|<2**-21, return -log(|x|) =#
         if hx < Int32(0)