[qtbase] Skip rootfs in QStorageInfo. Contributes to JB#50211

Skips rootfs device since there is another device for /. It may exist
because / has been pivot from rootfs to ext4 on boot but it's typically
not useful. This allows another device mounted to the same mount point
to overwrite rootfs device.

Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

src/corelib/io/qstorageinfo_unix.cpp

@@ -459,7 +459,10 @@ void QStorageInfoPrivate::initRootPath()
         const QString mountDir = it.rootPath();
         const QByteArray fsName = it.fileSystemType();
         // we try to find most suitable entry
-        if (isParentOf(mountDir, oldRootPath) && maxLength < mountDir.length()) {
+        if (isParentOf(mountDir, oldRootPath)
+                && (maxLength < mountDir.length()
+                    // Alternative device that's not rootfs, overwrites pivoted root
+                    || (rootPath == mountDir && device == "rootfs"))) {
             maxLength = mountDir.length();
             rootPath = mountDir;
             device = it.device();