Switch triton_shared submodule to Meta fork

Microsoft's triton-shared repo (github.com/microsoft/triton-shared) is
no longer maintained. Switch to the actively maintained Meta fork at
github.com/facebookincubator/triton-shared.

The Meta fork was created from Microsoft's commit 08684f9. The submodule
is pinned to 1af6a5f (tip of Meta's main branch). The triton_shared.patch
has been regenerated against the new base.

No functional change — the underlying code is identical, and the patch
produces the same patched working tree.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: erwei-xilinx

.gitmodules

@@ -3,4 +3,4 @@
 	url = https://github.com/triton-lang/triton.git
 [submodule "third_party/triton_shared"]
 	path = third_party/triton_shared
-	url = https://github.com/microsoft/triton-shared.git
+	url = https://github.com/facebookincubator/triton-shared.git