udisksopticaldisc.cpp SharedContentTypesCache uses QSystemSemaphore +
QSharedMemory locking for a cross-process content-type cache; Redox Qt is built
without systemsemaphore-backed shared memory (same limitation the qtwayland
recipe notes), so it failed to compile ("m_semaphore not declared",
"QSharedMemory has no member named lock"). Guard the cache on
QT_CONFIG(sharedmemory) && QT_CONFIG(systemsemaphore); on Redox provide a
no-cache stub that detects directly (the cached path already fell back to
advancedDiscDetect()). Durable patch.
vasilito
16ac294f26