kf6-solid: guard optical-disc shared cache (Redox has no QSystemSemaphore)

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.

local/recipes/kde/kf6-solid/recipe.toml

@@ -6,6 +6,12 @@ version = "6.28"
 [source]
 tar = "https://download.kde.org/stable/frameworks/6.28/solid-6.28.0.tar.xz"
 blake3 = "fc1c0f092ff6786a2284e57b57500e11ac47dcd5471e842e0898ce76c96ab8cb"
+patches = [
+    # Redox Qt lacks QSystemSemaphore + QSharedMemory locking, so the optical
+    # disc content-type shared cache (udisksopticaldisc.cpp) fails to compile.
+    # Guard it and fall back to direct detection.
+    "redox-no-systemsemaphore-optical-cache.patch",
+]
 
 [build]
 template = "custom"

local/recipes/kde/kf6-solid/redox-no-systemsemaphore-optical-cache.patch

@@ -0,0 +1,29 @@
+--- a/src/solid/devices/backends/udisks2/udisksopticaldisc.cpp
++++ b/src/solid/devices/backends/udisks2/udisksopticaldisc.cpp
+@@ -186,6 +186,7 @@
+     QPair<OpticalDisc::Identity, Solid::OpticalDisc::ContentTypes> m_info[100];
+ };
+ 
++#if QT_CONFIG(sharedmemory) && QT_CONFIG(systemsemaphore)
+ class SharedContentTypesCache
+ {
+ private:
+@@ -295,6 +296,18 @@
+         m_shmem.detach();
+     }
+ };
++#else
++// Redox and other platforms without QSystemSemaphore + QSharedMemory locking:
++// there is no cross-process content-type cache; detect directly each call.
++class SharedContentTypesCache
++{
++public:
++    Solid::OpticalDisc::ContentTypes getContent(const OpticalDisc::Identity &, const QByteArray &file)
++    {
++        return advancedDiscDetect(file);
++    }
++};
++#endif // QT_CONFIG(sharedmemory) && QT_CONFIG(systemsemaphore)
+ 
+ Q_GLOBAL_STATIC(QThreadStorage<SharedContentTypesCache>, sharedContentTypesCache)
+