Use old API for old LLVM versions

Author: raulcd

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()); }