Merge bitcoin#22342: Avoid the use of P0083R3 std::set::merge

6cf4ea7 Avoid the use of P0083R3 std::set::merge (Pieter Wuille)

Pull request description:

  This use was introduced in bitcoin#21365, but as pointed out in bitcoin#22339, this causes compatibility problems.

  Just avoid its use for now.

ACKs for top commit:
  jonatack:
    re-ACK 6cf4ea7
  benthecarman:
    ACK 6cf4ea7
  hebasto:
    ACK 6cf4ea7, successfully compiled on the following systems:

Tree-SHA512: 2b3fdcadb7de98963ebb0b192bd956aa68526457fe5b374c74a69ea10d5b68902763148f11abbcc471010bcdc799e0804faef5f8e8ff8a509b3a053c0cb0ba39

Author: MarcoFalke

src/script/standard.cpp

@@ -407,7 +407,13 @@ void TaprootSpendData::Merge(TaprootSpendData other)
         merkle_root = other.merkle_root;
     }
     for (auto& [key, control_blocks] : other.scripts) {
-        scripts[key].merge(std::move(control_blocks));
+        // Once P0083R3 is supported by all our targeted platforms,
+        // this loop body can be replaced with:
+        // scripts[key].merge(std::move(control_blocks));
+        auto& target = scripts[key];
+        for (auto& control_block: control_blocks) {
+            target.insert(std::move(control_block));
+        }
     }
 }