Add missing documentation for some variables

Task-number: QTBUG-5109
Change-Id: I38e12b957cad099d2f815a0d192cf3ab9fee52e5
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
QColumnView: don't set an invalid index as the current one

When any item in a QColumnView gets selected, the next column gets
normally set to show the children of that index. When we are on a leaf
of a tree model, the next column will have an invalid root index, yet
we set that root index as the "current index" for the current column.

Due to the special handling for invalid indexes in
QAbstractItemView::setCurrentIndex, this ends up breaking the current
item AND the current selection in that column. Further clicks inside
the column for instance trigger the entire column (up to the clicked
index) to get selected, because of that broken first setCurrentIndex.

The simple fix is to stop doing that when the next column has
an invalid root index.

Task-number: QTBUG-2329
Change-Id: Icd10c0b958e25cd868536e1315561787977b68bd
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
WinRT: Only set keepalive socket option in certain socket states

The keepalive socket can only be set if the socket is not connected
(see
http://msdn.microsoft.com/en-us/library/ie/windows.networking.sockets.streamsocketcontrol.keepalive)

Task-number: QTBUG-38623
Change-Id: Ia40dc66f071a8109538e4be7a8f420de81d5be8d
Reviewed-by: Alex Trotsenko <alex1973tr@gmail.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>
Reviewed-by: Andrew Knight <andrew.knight@theqtcompany.com>
Android: Enable -fno-builtin-memmove in arm builds

On some devices, a miscompilation of libc.so has caused it to
return the wrong value. Instead of returning the dest pointer,
it returns dest + n. When compiling with optimizations turned
on, gcc may use this return value for subsequent accesses to
dest after the memmove() call, causing memory corruption.

This caused problems e.g. in QVector::prepend() which would
overwrite the whole vector with the new value.

Setting -fno-builtin-memmove disables the optimization and
works around this bug with very little risk or impact.

More information in:
     http://code.google.com/p/android/issues/detail?id=81692

[ChangeLog][Android] Fixed device-specific crash on Samsung
Galaxy Tab 3 Lite 7" and some other devices.

Task-number: QTBUG-34984
Change-Id: I0c1347149eb5fe1c298758fe7de81aca4137f652
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>