[hipRTC] add lowest() for float to MIOpen custom limits (#2753)

* [hipRTC] add lowest() to MIOpen custom limits

* the earliest trace can be found together with numeric_limits<int>

Author: junliume

src/kernels/miopen_limits.hpp

@@ -46,6 +46,10 @@ class numeric_limits<float>
     static constexpr __device__ float max() noexcept { return 0x1.FFFFFEp+127f; }
 
     static constexpr __device__ float min() noexcept { return 0x1p-126f; }
+
+#if HIP_PACKAGE_VERSION_FLAT >= 6001024024ULL
+    static constexpr __device__ float lowest() noexcept { return -0x1.fffffep+127; }
+#endif
 };
 
 template <>