Qt 5.12.10 fails to build from source for Android < 24

Android API level 16 is a reference platform for Qt 5.12, at least for armv7. However, Qt 5.12.10 fails to build from source with API level 16, due to use of Activity::isInMultiWindowMode(), available only since API level 24.

2020-12-19T11:09:49.5784590Z javac -source 6 -target 6 -Xlint:unchecked -bootclasspath /Users/runner/Library/Android/sdk/platforms/android-16/android.jar -cp /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/:/Users/runner/Library/Android/sdk/platforms/android-16/android.jar -d .classes /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/accessibility/QtAccessibilityDelegate.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/accessibility/QtNativeAccessibility.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtActivityDelegate.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtEditText.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtInputConnection.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtLayout.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtMessageDialogHelper.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtNative.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtNativeLibrariesDir.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtSurface.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/ExtractStyle.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/EditContextView.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/EditPopupMenu.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/CursorHandle.java /Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtThread.java
2020-12-19T11:09:52.6097760Z ##[error]/Users/runner/work/1/s/build/source/qtbase-everywhere-src-5.12.10-0/src/android/jar/src/org/qtproject/qt5/android/QtActivityDelegate.java:881: error: cannot find symbol
2020-12-19T11:09:52.6202430Z if (Build.VERSION.SDK_INT < 24 || !m_activity.isInMultiWindowMode())
2020-12-19T11:09:52.6303880Z ^
2020-12-19T11:09:52.6405080Z symbol: method isInMultiWindowMode()
2020-12-19T11:09:52.6506220Z location: variable m_activity of type Activity

There is just one related change since 5.12.9:
https://codereview.qt-project.org/q/I03a561459b2aa04c808b7d4220cd3e558671dd17