apacheGH-47469: [C++][Gandiva] Add support for LLVM 21.1.0 (apache#47473)

LLVM 21.1 was released and some of our CI jobs are failing.

* Accept LLVM 21.1
* Don't use deprecated API

Two of the related commits that changed APIs on LLVM are:
- llvm/llvm-project@034f2b3
- llvm/llvm-project@b18e5b6

Yes on CI

No

* GitHub Issue: apache#47469

Authored-by: Raúl Cumplido <raulcumplido@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

Author: raulcd

cpp/src/gandiva/engine.cc

@@ -200,10 +200,16 @@ Status UseJITLinkIfEnabled(llvm::orc::LLJITBuilder& jit_builder) {
   static auto maybe_use_jit_link = ::arrow::internal::GetEnvVar("GANDIVA_USE_JIT_LINK");
   if (maybe_use_jit_link.ok()) {
     ARROW_ASSIGN_OR_RAISE(static auto memory_manager, CreateMemmoryManager());
+#  if LLVM_VERSION_MAJOR >= 21
+    jit_builder.setObjectLinkingLayerCreator([&](llvm::orc::ExecutionSession& ES) {
+      return std::make_unique<llvm::orc::ObjectLinkingLayer>(ES, *memory_manager);
+    });
+#  else
     jit_builder.setObjectLinkingLayerCreator(
         [&](llvm::orc::ExecutionSession& ES, const llvm::Triple& TT) {
           return std::make_unique<llvm::orc::ObjectLinkingLayer>(ES, *memory_manager);
         });
+#  endif
   }
   return Status::OK();
 }

cpp/src/gandiva/llvm_types.h

@@ -56,7 +56,11 @@ class GANDIVA_EXPORT LLVMTypes {
   llvm::Type* double_type() { return llvm::Type::getDoubleTy(context_); }
 
   llvm::PointerType* ptr_type(llvm::Type* type) {
+#if LLVM_VERSION_MAJOR >= 21
+    return llvm::PointerType::get(context_, 0);
+#else
     return llvm::PointerType::get(type, 0);
+#endif
   }
 
   llvm::PointerType* i8_ptr_type() { return ptr_type(i8_type()); }