Merge #2870: Update librustzcash

60b6468 Add git repo to cargo.offline (Duddino Gatto)
aefa4d3 Update rust unit tests (Alessandro Rezzi)
4c77aed Update librustzcash (Duddino)

Pull request description:

  Updates librustzcash to version 0.11.0
  I'm depending on [a modified version](https://github.com/Duddino/librustzcash/tree/pivx), this is because some methods are not made public by upstream and to strip Orchard since its license is incompatible with MIT

ACKs for top commit:
  panleone:
    re-tACK 60b6468 not passing tests are clearly not linked to the PR
  Fuzzbawls:
    ACK 60b6468
  Liquid369:
    tACK 60b6468

Tree-SHA512: 28d9f2ee0e62050d612f51156d2508a229a792c353eddfd4423d8f8c420060a469da059cdde38d9bbd197a7e8a59b24be6338a6e080aab98585e309071b31935

.cargo/config.offline

@@ -1,5 +1,10 @@
 [source.crates-io]
 replace-with = "vendored-sources"
 
+[source."git+https://github.com/PIVX-Project/librustzcash?rev=e7662b23d16c38595ef9ad1f3ae683b1f54dc732"]
+git = "https://github.com/PIVX-Project/librustzcash"
+rev = "e7662b23d16c38595ef9ad1f3ae683b1f54dc732"
+replace-with = "vendored-sources"
+
 [source.vendored-sources]
 # The directory for this source is set to RUST_VENDORED_SOURCES by src/Makefile.am