[backport] Workaround compiler issue on Windows. (dmlc#11916)

Author: trivialfis

src/tree/param.h

@@ -242,14 +242,14 @@ XGBOOST_DEVICE inline T CalcGainGivenWeight(const TrainingParams &p, T sum_grad,
 
 // calculate weight given the statistics
 template <typename TrainingParams, typename T>
-XGBOOST_DEVICE inline T CalcWeight(const TrainingParams &p, T sum_grad,
-                                   T sum_hess) {
+XGBOOST_DEVICE std::enable_if_t<std::is_floating_point_v<T>, T> CalcWeight(TrainingParams const &p,
+                                                                           T sum_grad, T sum_hess) {
   if (sum_hess < p.min_child_weight || sum_hess <= 0.0) {
     return 0.0;
   }
   T dw = -ThresholdL1(sum_grad, p.reg_alpha) / (sum_hess + p.reg_lambda);
-  if (p.max_delta_step != 0.0f && std::abs(dw) > p.max_delta_step) {
-    dw = std::copysign(p.max_delta_step, dw);
+  if (p.max_delta_step != 0.0f && ::fabs(dw) > p.max_delta_step) {
+    dw = ::copysign(p.max_delta_step, dw);
   }
   return dw;
 }