Bug 876: implement a portable log1p function
Bug 876: implement a portable log1p function

ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,Zefz/eigen,TSC21/Eigen,toastedcrumpets/eigen,Zefz/eigen,toastedcrumpets/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,toastedcrumpets/eigen,Zefz/eigen,Zefz/eigen,ritsu1228/eigen,pasuka/eigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,pasuka/eigen,TSC21/Eigen,TSC21/Eigen,pasuka/eigen,toastedcrumpets/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,pasuka/eigen,TSC21/Eigen,ritsu1228/eigen