math: Make signbit return Bool

Author: jpsamaroo

src/device/gcn/math.jl

@@ -63,7 +63,7 @@ for jltype in (Float32, Float64)
     push!(MATH_INTRINSICS, GCNIntrinsic(:isfinite; inp_args=(jltype,), out_arg=Int32, tobool=true))
     push!(MATH_INTRINSICS, GCNIntrinsic(:isinf; inp_args=(jltype,), out_arg=Int32, tobool=true))
     push!(MATH_INTRINSICS, GCNIntrinsic(:isnan; inp_args=(jltype,), out_arg=Int32, tobool=true))
-    push!(MATH_INTRINSICS, GCNIntrinsic(:signbit; inp_args=(jltype,), out_arg=Int32))
+    push!(MATH_INTRINSICS, GCNIntrinsic(:signbit; inp_args=(jltype,), out_arg=Int32, tobool=true))
 end
 
 for intr in MATH_INTRINSICS