Add filename and SHA256 hash for Windows Rust package
When running `make download` in the `depends` directory, the `download-win` target (which `download` depends on) generates an error when it runs the commands defined in `check_or_remove_sources`:
```Makefile
sha256sum: /home/vagrant/zcash/depends/work/download/rust-1.16.0/..hash: no properly formatted SHA256 checksum lines found
funcs.mk:242: recipe for target '/home/vagrant/gitian-builder/cache/common/download-stamps/.stamp_fetched-rust-.hash' failed
make[1]: *** [/home/vagrant/gitian-builder/cache/common/download-stamps/.stamp_fetched-rust-.hash] Error 1
make[1]: Leaving directory '/home/vagrant/zcash/depends'
Makefile:153: recipe for target 'download-win' failed
make: *** [download-win] Error 2
```
The reason for the error is that `depends/packages/rust.mk` defines `rust_file_name_linux` and `rust_file_name_darwin` but leaves `rust_file_name_mingw32` undefined.
A directory of available rust downloads is here: https://static.rust-lang.org/dist/index.html
The closest windows analog in that list (using the same version number as currently defined in `rust.mk`) appears to be `rust-mingw-1.16.0-x86_64-pc-windows-gnu.tar.gz`. A corresponding sha256 value is also given in `rust-mingw-1.16.0-x86_64-pc-windows-gnu.tar.gz.sha256`.
After adding these values to `rust.mk`, the rust-mingw tar package was downloaded along with the rest of the dependencies and the above error message went away.
Update boost to 1.66.0
- Remove no longer required patch `deprecated_auto_ptr.patch`.
- Remove potentially no longer required patch `include_poll.patch`. This might cause a regression for unsupported platform Alpine Linux (see #1559)
Split declaration and definition of SPROUT_BRANCH_ID constant
Fixes an initialization-order-fiasco error detected by ASan:
https://ci.z.cash/#/builders/7/builds/149
Disable auto-deprecation on regtest and testnet
Prevents auto-senescence based on @str4d's recommendation to early return out of `EnforceNodeDeprecation` if net is not `main`.
Closes#2876.
Co-authored-by: Marshall Gaucher <marshall@z.cash>
[macOS] Fix test/gtest bugs caught by latest clang
Tests fail with latest clang on macOS (clang-900.0.39.2)
```
test/rpc_wallet_tests.cpp:1064:26: error: implicit conversion from 'double' to 'CAmount' (aka 'long long') changes value from 123.456 to 123 [-Werror,-Wliteral-conversion]
test/rpc_wallet_tests.cpp:1071:18: error: implicit conversion from 'double' to 'CAmount' (aka 'long long') changes value from 1.111 to 1 [-Werror,-Wliteral-conversion]
gtest/test_deprecation.cpp:28:1: error: control reaches end of non-void function [-Werror,-Wreturn-type]
```
Part of #2246.