Integrate LLVM at llvm/llvm-project@c660b281b600

Updates LLVM usage to match
[c660b281b600](llvm/llvm-project@c660b281b600)

PiperOrigin-RevId: 710060595

third_party/llvm/generated.patch

@@ -1 +1,22 @@
 Auto generated patch. Do not edit or delete it, even if empty.
+diff -ruN --strip-trailing-cr a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
+--- a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
++++ b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel
+@@ -1619,13 +1619,16 @@
+
+ cc_library(
+     name = "FrontendAtomic",
++    srcs = glob([
++        "lib/Frontend/Atomic/*.cpp",
++    ]),
+     hdrs = glob([
+         "include/llvm/Frontend/Atomic/*.h",
+     ]),
+     copts = llvm_copts,
+     deps = [
++        ":Core",
+         ":Support",
+-        ":ir_headers",
+     ],
+ )
+

third_party/llvm/workspace.bzl

@@ -4,8 +4,8 @@ load("//third_party:repo.bzl", "tf_http_archive")
 
 def repo(name):
     """Imports LLVM."""
-    LLVM_COMMIT = "21a1dbb50320889ee0e116237c924ee1af3c3dd3"
-    LLVM_SHA256 = "399bab11e4de85d9d65957ccf236ec57c1741ec6ed96225a86076b34e0026816"
+    LLVM_COMMIT = "c660b281b60085cbe40d73d692badd43d7708d20"
+    LLVM_SHA256 = "77714a6dbfab00cb7a8d54ae119770011c9da9d810ea02864b173fce90b4ca14"
 
     tf_http_archive(
         name = name,