Merge #20156: build: Make sqlite support optional (compile-time)

bbb42a6896 RPC: createwallet: Nicer error message if descriptor wallet requested and sqlite support not compiled in (Luke Dashjr)
6608fec332 GUI: Create Wallet: Nicely disable descriptor wallet checkbox if sqlite support not compiled in (Luke Dashjr)
7b54d768e1 Make sqlite support optional (compile-time) (Luke Dashjr)

Pull request description:

  As a new requirement, sqlite support should be optional. This PR aims to be only minimum/blocker changes for 0.21.

  Potential follow-up PRs after this:
  * Make BDB support optional
  * Nicer error messages when user tries to load an unsupported wallet
  * Don't compile descriptor wallet code if sqlite disabled

ACKs for top commit:
  jonasschnelli:
    Tested ACK bbb42a6896
  achow101:
    ACK bbb42a6896
  Sjors:
    re-utACK bbb42a6896
  hebasto:
    ACK bbb42a6896, tested on Linux Mint 20 (x86_64, Qt 5.12.8).

Tree-SHA512: 500209dd1971310fab8ae51543343ce0ba91f088ccccff6109b4cc27547cd5532289dca6cb7dac2a7d7c59cdf3c8f5aacc31e9b0f912e38cea52ec26b97100bd

src/qt/createwalletdialog.cpp

@@ -34,6 +34,12 @@ CreateWalletDialog::CreateWalletDialog(QWidget* parent) :
             ui->disable_privkeys_checkbox->setChecked(false);
         }
     });
+
+#ifndef USE_SQLITE
+    ui->descriptor_checkbox->setToolTip(tr("Compiled without sqlite support (required for descriptor wallets)"));
+    ui->descriptor_checkbox->setEnabled(false);
+    ui->descriptor_checkbox->setChecked(false);
+#endif
 }
 
 CreateWalletDialog::~CreateWalletDialog()