Merge bitcoin#15167: qt: Fix wallet selector size adjustment

ca91661 Fix wallet selector size adjustment (Hennadii Stepanov)

Pull request description:

  This PR sets `QComboBox::AdjustToContents` instead of default `QComboBox::AdjustToContentsOnFirstShow` for wallet selectors.

  Before (in master):
  ![screenshot from 2019-01-14 20-47-22](https://user-images.githubusercontent.com/32963518/51133771-83d00d80-183e-11e9-812c-3a1119fa766e.png)

  After (with this PR):
  ![screenshot from 2019-01-14 20-48-43](https://user-images.githubusercontent.com/32963518/51133788-90546600-183e-11e9-8394-eb62a998b90f.png)

Tree-SHA512: c23ac91905bb31aaa32f2fccc02b01f5707d8b094020fe6a75a9e099e78f9191670474920234a01c46480f67d3d311f44ff46f1f4202cd50a4a6d4d09a8342ce

src/qt/bitcoingui.cpp

@@ -614,6 +614,7 @@ void BitcoinGUI::createToolBars()
 
 #ifdef ENABLE_WALLET
         m_wallet_selector = new QComboBox(this);
+        m_wallet_selector->setSizeAdjustPolicy(QComboBox::AdjustToContents);
         connect(m_wallet_selector, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &BitcoinGUI::setCurrentWalletBySelectorIndex);
 
         QVBoxLayout* walletSelectorLayout = new QVBoxLayout(this);

src/qt/forms/debugwindow.ui

@@ -604,6 +604,9 @@
          </item>
          <item>
           <widget class="QComboBox" name="WalletSelector">
+           <property name="sizeAdjustPolicy">
+            <enum>QComboBox::AdjustToContents</enum>
+           </property>
            <item>
             <property name="text">
              <string>(none)</string>