message: Added some factors that affect the dependency list
diff: @@ -17,6 +17,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
  | libevent | [2.1.8-stable](https://github.com/libevent/libevent/releases) | 2.0.22 | No | | |
  | libjpeg | | | | | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L65) |
  | libpng | | | | | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L64) |
  +| libsrvg | | | | | |
  | MiniUPnPc | [2.0.20180203](http://miniupnp.free.fr/files) | | No | | |
  | OpenSSL | [1.0.1k](https://www.openssl.org/source) | | Yes | | |
  | PCRE | | | | | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L66) |
  @@ -28,3 +29,18 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
  | xkbcommon | | | | | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L86) (Linux only) |
  | ZeroMQ | [4.3.1](https://github.com/zeromq/libzmq/releases) | 4.0.0 | No | | |
  | zlib | [1.2.11](https://zlib.net/) | | | | No |
  +
  +Controlling dependencies
  +------------------------
  +Some dependencies are not needed in all configurations. The following are some factors that affect the dependency list.
  +
  +#### Options passed to `./configure`
  +* MiniUPnPc is not needed with `--with-miniupnpc=no`.
  +* Berkeley DB is not needed with `--disable-wallet`.
  +* protobuf is not needed with `--disable-bip70`.
  +* Qt is not needed with `--without-gui`.
  +* If the qrencode dependency is absent, QR support won't be added. To force an error when that happens, pass `--with-qrencode`.
  +* ZeroMQ is needed only with the `--with-zmq` option.
  +
  +#### Other
  +* librsvg is only needed if you need to run `make deploy` on (cross-compliation to) macOS.
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