jit: Adjust AArch64-only code for LLVM 21.

LLVM 21 changed the arguments of RTDyldObjectLinkingLayer's
constructor, breaking compilation with the backported
SectionMemoryManager from commit 9044fc1d.

cd585864c0

Backpatch-through: 14
Author: Holger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/d25e6e4a-d1b4-84d3-2f8a-6c45b975f53d%40applied-asynchrony.com

src/backend/jit/llvm/llvmjit_wrap.cpp

@@ -118,7 +118,14 @@ DEFINE_SIMPLE_CONVERSION_FUNCTIONS(llvm::orc::ObjectLayer, LLVMOrcObjectLayerRef
 LLVMOrcObjectLayerRef
 LLVMOrcCreateRTDyldObjectLinkingLayerWithSafeSectionMemoryManager(LLVMOrcExecutionSessionRef ES)
 {
+#if LLVM_VERSION_MAJOR >= 21
+	return wrap(new llvm::orc::RTDyldObjectLinkingLayer(
+		*unwrap(ES), [](const llvm::MemoryBuffer&) {
+			return std::make_unique<llvm::backport::SectionMemoryManager>(nullptr, true);
+		}));
+#else
 	return wrap(new llvm::orc::RTDyldObjectLinkingLayer(
 		*unwrap(ES), [] { return std::make_unique<llvm::backport::SectionMemoryManager>(nullptr, true); }));
+#endif
 }
 #endif