fix(build): Handle namespace packages for PyPI CUDA detection (#2580)

fix: handle nvidia namespace packages where __file__ is None
Signed-off-by: Santosh Bhavani <santosh.bhavani@live.com>
Co-authored-by: Kirthi Shankar Sivamani <ksivamani@nvidia.com>

transformer_engine/common/__init__.py

@@ -245,11 +245,13 @@ def _nvidia_cudart_include_dir() -> str:
         return ""
 
     # Installing some nvidia-* packages, like nvshmem, create nvidia name, so "import nvidia"
-    # above doesn't through. However, they don't set "__file__" attribute.
-    if nvidia.__file__ is None:
-        return ""
+    # above doesn't throw. However, they don't set "__file__" attribute.
+    if nvidia.__file__ is not None:
+        nvidia_root = Path(nvidia.__file__).parent
+    else:
+        nvidia_root = Path(nvidia.__path__[0])  # namespace package
 
-    include_dir = Path(nvidia.__file__).parent / "cuda_runtime"
+    include_dir = nvidia_root / "cuda_runtime"
     return str(include_dir) if include_dir.exists() else ""