Softmax (#546)

* add test layernorm g-mem version

* Delete include/configure directory

* Delete examples/test_layernorm directory

* Update gemm_with_softmax.h

* Update gemm_softmax.cu

* Update linear_combination.h

* Update fast_math.h

* remove redundant vars

Co-authored-by: yujia.zhai <yujia.zhai@bytedance.com>
Co-authored-by: yuzhai <yuzhai@nvidia.com>

include/cutlass/fast_math.h

@@ -718,11 +718,11 @@ double fast_exp(double x) {
 }
 
 CUTLASS_HOST_DEVICE
-float fast_exp(half_t x) {
+half_t fast_exp(half_t x) {
   #if defined(__CUDA_ARCH__) && (__CUDACC_VER_MAJOR__ >= 10) && (__CUDA_ARCH__ >= 750)
-      return ::hexp(x.to_half());
+      return (half_t)(::hexp(x.to_half()));
   #else
-      return fast_exp(float(x));
+      return (half_t)(fast_exp(float(x)));
   #endif
 }
 
@@ -908,4 +908,3 @@ T absolute_value(T x) {
 }  // namespace cutlass
 
 /////////////////////////////////////////////////////////////////////////////////////////////////
-