Fix compilation with gcc-9+ (#3262)

Summary:
To fix `cannot resolve overloaded function ‘isinf’ based on conversion to type ‘torch::executor::FunctionRef<bool(double)>’` error

Not sure how it ever worked before see https://godbolt.org/z/939YKdjqW

Pull Request resolved: #3262

Reviewed By: kimishpatel, manuelcandales

Differential Revision: D56501235

Pulled By: malfet

fbshipit-source-id: 6f89beef9fd56a80ecbb2df573821da95b2da746

Author: malfet

kernels/portable/cpu/op_isinf.cpp

@@ -15,7 +15,8 @@ namespace executor {
 namespace native {
 
 Tensor& isinf_out(RuntimeContext& ctx, const Tensor& in, Tensor& out) {
-  return internal::unary_ufunc_realhb_to_bool(std::isinf, ctx, in, out);
+  return internal::unary_ufunc_realhb_to_bool(
+      static_cast<bool (*)(double)>(std::isinf), ctx, in, out);
 }
 
 } // namespace native

kernels/portable/cpu/op_isnan.cpp

@@ -15,7 +15,8 @@ namespace executor {
 namespace native {
 
 Tensor& isnan_out(RuntimeContext& ctx, const Tensor& in, Tensor& out) {
-  return internal::unary_ufunc_realhb_to_bool(std::isnan, ctx, in, out);
+  return internal::unary_ufunc_realhb_to_bool(
+      static_cast<bool (*)(double)>(std::isnan), ctx, in, out);
 }
 
 } // namespace native