Merge #2650: Update bls-signatures subtree to latest version

bc84ff0 Doc: add bls-sigs repo to developer-notes subtrees section (furszy)
9daeb29 Squashed 'src/chiabls/' changes from bc64f128f0..eaf7d2d1a4 (furszy)

Pull request description:

  Updating the bls-signatures subtree, reason is PIVX-Project/bls-signatures#11 (which gladly was detected before v6.0).
  Coming from #2631 investigation.

  Pulling up to PIVX-Project/bls-signatures@eaf7d2d.

ACKs for top commit:
  random-zebra:
    utACK bc84ff0

Tree-SHA512: 91744a317eb8834bdac792a2cfc0fca306bb63798ec037743057c87238087c68b2bceca5811d6fdb9865a8a3ba5f5dd7268bebd398bc2d80223cd3e1baa625bd

doc/developer-notes.md

@@ -729,6 +729,9 @@ Current subtrees include:
 - src/univalue
   - Upstream at https://github.com/bitcoin-core/univalue ; actively maintained by Core contributors, deviates from upstream https://github.com/jgarzik/univalue
 
+- src/chiabls
+  - Upstream at https://github.com/PIVX-Project/bls-signatures/ ; actively maintained by Core contributors, deviates from upstream https://github.com/Chia-Network/bls-signatures/
+
 Upgrading LevelDB
 ---------------------
 

src/chiabls/src/privatekey.cpp

@@ -87,6 +87,7 @@ PrivateKey& PrivateKey::operator=(const PrivateKey& other)
 {
     CheckKeyData();
     other.CheckKeyData();
+    InvalidateCaches();
     bn_copy(keydata, other.keydata);
     return *this;
 }

src/chiabls/src/test.cpp

@@ -63,8 +63,12 @@ TEST_CASE("class PrivateKey") {
         REQUIRE(!pk3.IsZero());
         REQUIRE(pk1 != pk2);
         REQUIRE(pk3 == pk2);
+        REQUIRE(pk2.GetG1Element().IsValid()); // cache previous g1
+        REQUIRE(pk2.GetG2Element().IsValid()); // cache previous g2
         pk2 = pk1;
         REQUIRE(pk1 == pk2);
+        REQUIRE(pk1.GetG1Element() == pk2.GetG1Element());
+        REQUIRE(pk1.GetG2Element() == pk2.GetG2Element());
         REQUIRE(pk3 != pk2);
     }
     SECTION("Move {constructor|assignment operator}") {