Merge #16257: [wallet] abort when attempting to fund a transaction above -maxtxfee

806b0052c3b45415862f74f20ba5f389e5b673de [wallet] abort when attempting to fund a transaction above maxtxfee (Sjors Provoost)

Pull request description:

  `FundTransaction` calls `GetMinimumFee` which, when the fee rate is absurdly high, quietly reduces the fee to `-maxtxfee`.

  Becaue an absurdly high fee rate is usually the result of a fat finger, aborting seems safer behavior.

  Before:
  ```
  bitcoin-cli walletcreatefundedpsbt '[]' '[{"tb1q...": 0.01}]' 0 '{"feeRate": 10}' true
  {
    "psbt": "cHNidP8...gAA=",
    "fee": 0.10000000,
    "changepos": 1
  }

  ```

  After:
  ```
  bitcoin-cli walletcreatefundedpsbt '[]' '[{"tb1q...": 0.01}]' 0 '{"feeRate": 10}' true
  error code: -25
  error message:
  Fee exceeds maximum configured by -maxtxfee
  ```

  QT still checks the max fee rate as expected:
  <img width="566" alt="Schermafbeelding 2019-06-20 om 19 52 00" src="https://user-images.githubusercontent.com/10217/59888424-a2aa7100-9395-11e9-8ae6-8a3c1f7de585.png">

ACKs for top commit:
  laanwj:
    Code review ACK 806b0052c3b45415862f74f20ba5f389e5b673de

Tree-SHA512: bee95811711cdab100b614d2347921407af3b400aea613ca156953ed3f60b924ad29a1d335bd0e240c0b7c0fbb360226bab03294d226a5560cdf2a3f21e6d406

0 files changed, 0 insertions, 0 deletions