Unrolled build for rust-lang#140400

Rollup merge of rust-lang#140400 - durin42:llvm-21-getguid, r=cuviper

PassWrapper: adapt for llvm/llvm-project@d3d856ad8469

LLVM 21 moves to making it more explicit what this function call is doing, but nothing has changed behaviorally, so for now we just adjust to using the new name of the function.

`@rustbot` label llvm-main

Author: rust-timer

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -1365,7 +1365,12 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules, size_t num_modules,
   // Convert the preserved symbols set from string to GUID, this is then needed
   // for internalization.
   for (size_t i = 0; i < num_symbols; i++) {
+#if LLVM_VERSION_GE(21, 0)
+    auto GUID =
+        GlobalValue::getGUIDAssumingExternalLinkage(preserved_symbols[i]);
+#else
     auto GUID = GlobalValue::getGUID(preserved_symbols[i]);
+#endif
     Ret->GUIDPreservedSymbols.insert(GUID);
   }
 
@@ -1685,11 +1690,11 @@ extern "C" void LLVMRustComputeLTOCacheKey(RustStringRef KeyOut,
   // Based on the 'InProcessThinBackend' constructor in LLVM
 #if LLVM_VERSION_GE(21, 0)
   for (auto &Name : Data->Index.cfiFunctionDefs().symbols())
-    CfiFunctionDefs.insert(
-        GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(Name)));
+    CfiFunctionDefs.insert(GlobalValue::getGUIDAssumingExternalLinkage(
+        GlobalValue::dropLLVMManglingEscape(Name)));
   for (auto &Name : Data->Index.cfiFunctionDecls().symbols())
-    CfiFunctionDecls.insert(
-        GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(Name)));
+    CfiFunctionDecls.insert(GlobalValue::getGUIDAssumingExternalLinkage(
+        GlobalValue::dropLLVMManglingEscape(Name)));
 #else
   for (auto &Name : Data->Index.cfiFunctionDefs())
     CfiFunctionDefs.insert(