Add ext_qt patch for Windows to support fractional DPI scaling
This adds a series of patches related to QTBUG-53022 [1] for Windows to
allow enabling support for fractional DPI scaling.
These series of patches adds the option
QGuiApplication::setHighDpiScaleFactorRoundingPolicy to control how
the DPI scale factor is rounded (or not), which can also be overridden
by the environment variable QT_SCALE_FACTOR_ROUNDING_POLICY. The
options include:
- Round: Round up for .5 and above.
- Ceil: Always round up.
- Floor: Always round down.
- RoundPreferFloor: Round up for .75 and above.
- PassThrough: Don't round.
Currently the default option is explicitly set to Round to obtain the
old behaviour (where 1.5x is rounded to 2x).
Ref: