add some patches for building qt-5.12.2

docs/qt512.2_avoid_qtabbar_segfault.patch

@@ -0,0 +1,11 @@
+--- qtbase/src/widgets/widgets/qtabbar.cpp.orig	2019-03-19 12:24:14.000000000 -0400
++++ qtbase/src/widgets/widgets/qtabbar.cpp	2019-03-19 12:23:40.000000000 -0400
+@@ -738,6 +738,8 @@
+ {
+     Q_Q(QTabBar);
+     Q_ASSERT(index >= 0);
++    // play it safe
++    if (index < 0) return;
+
+     Tab &tab = tabList[index];
+     bool vertical = verticalTabs(shape);

docs/qt512.2_qtableview_fix.patch

@@ -0,0 +1,68 @@
+diff --git qtbase/src/widgets/styles/qcommonstyle.cpp qtbase/src/widgets/styles/qcommonstyle.cpp
+index 79e338a6e7..c739ddc6e2 100644
+--- qtbase/src/widgets/styles/qcommonstyle.cpp
++++ qtbase/src/widgets/styles/qcommonstyle.cpp
+@@ -843,11 +843,14 @@ static void drawArrow(const QStyle *style, const QStyleOptionToolButton *toolbut
+ }
+ #endif // QT_CONFIG(toolbutton)
+
+-static QSizeF viewItemTextLayout(QTextLayout &textLayout, int lineWidth)
++static QSizeF viewItemTextLayout(QTextLayout &textLayout, int lineWidth, int maxHeight = -1, int *lastVisibleLine = nullptr)
+ {
++    if (lastVisibleLine)
++        *lastVisibleLine = -1;
+     qreal height = 0;
+     qreal widthUsed = 0;
+     textLayout.beginLayout();
++    int i = 0;
+     while (true) {
+         QTextLine line = textLayout.createLine();
+         if (!line.isValid())
+@@ -856,6 +859,13 @@ static QSizeF viewItemTextLayout(QTextLayout &textLayout, int lineWidth)
+         line.setPosition(QPointF(0, height));
+         height += line.height();
+         widthUsed = qMax(widthUsed, line.naturalTextWidth());
++        // we assume that the height of the next line is the same as the current one
++        if (maxHeight > 0 && lastVisibleLine && height + line.height() > maxHeight) {
++            const QTextLine nextLine = textLayout.createLine();
++            *lastVisibleLine = nextLine.isValid() ? i : -1;
++            break;
++        }
++        ++i;
+     }
+     textLayout.endLayout();
+     return QSizeF(widthUsed, height);
+@@ -869,7 +879,13 @@ QString QCommonStylePrivate::calculateElidedText(const QString &text, const QTex
+     QTextLayout textLayout(text, font);
+     textLayout.setTextOption(textOption);
+
+-    viewItemTextLayout(textLayout, textRect.width());
++    // In AlignVCenter mode when more than one line is displayed and the height only allows
++    // some of the lines it makes no sense to display those. From a users perspective it makes
++    // more sense to see the start of the text instead something inbetween.
++    const bool vAlignmentOptimization = paintStartPosition && valign.testFlag(Qt::AlignVCenter);
++
++    int lastVisibleLine = -1;
++    viewItemTextLayout(textLayout, textRect.width(), vAlignmentOptimization ? textRect.height() : -1, &lastVisibleLine);
+
+     const QRectF boundingRect = textLayout.boundingRect();
+     // don't care about LTR/RTL here, only need the height
+@@ -896,7 +912,7 @@ QString QCommonStylePrivate::calculateElidedText(const QString &text, const QTex
+         const int start = line.textStart();
+         const int length = line.textLength();
+         const bool drawElided = line.naturalTextWidth() > textRect.width();
+-        bool elideLastVisibleLine = false;
++        bool elideLastVisibleLine = lastVisibleLine == i;
+         if (!drawElided && i + 1 < lineCount && lastVisibleLineShouldBeElided) {
+             const QTextLine nextLine = textLayout.lineAt(i + 1);
+             const int nextHeight = height + nextLine.height() / 2;
+@@ -927,7 +943,8 @@ QString QCommonStylePrivate::calculateElidedText(const QString &text, const QTex
+         }
+
+         // below visible text, can stop
+-        if (height + layoutRect.top() >= textRect.bottom())
++        if ((height + layoutRect.top() >= textRect.bottom()) ||
++                (lastVisibleLine >= 0 && lastVisibleLine == i))
+             break;
+     }
+     return ret;