Fix __HIP_ARCH_* not defined after including math_functions.h

hcc_detail/math_functions.h used to include hcc_detail/hip_runtime.h.

Removing it has caused regression in TensorFlow 1.8.

Put it back for backward compatibiliity.


[ROCm/hip commit: b8a0c14171]

projects/hip/tests/src/deviceLib/hipTestIncludeMath.cpp

@@ -45,6 +45,14 @@ __device__ __host__ inline void throw_std_bad_alloc()
   #endif
 }
 
+// Test __HIP_ARCH_HAS_WARP_FUNNEL_SHIFT__ and __HIP_ARCH_HAS_DYNAMIC_PARALLEL__
+// is defined. Eigen HIP/hcc/Half.h __ldg depends on this.
+#if !defined(__HIP_ARCH_HAS_WARP_FUNNEL_SHIFT__) ||                            \
+    !defined(__HIP_ARCH_HAS_DYNAMIC_PARALLEL__)
+#error                                                                         \
+    "__HIP_ARCH_HAS_WARP_FUNNEL_SHIFT__ or __HIP_ARCH_HAS_DYNAMIC_PARALLEL__ not defined"
+#endif
+
 #include <hip/hip_runtime.h>
 #include "test_common.h"