Pull upstream patch for QTBUG-87010 which fixes a regression in Qt 5.15
causing QByteArray's that are returned by QIODevice::readLine() to consume
large amounts of memory. This is required to unbreak `astro/stellarium'
on e.g. i386, where `lconvert' utility runs out of 32-bit address space.

Reference: https://bugreports.qt.io/browse/QTBUG-87010
Approved by: kde (tcberner)