Metal: exclude tvOS from HDR compile gate

CAMetalLayer.wantsExtendedDynamicRangeContent and edrMetadata are not
exposed on the public tvOS SDK (they exist privately but are not part
of the tvOS public interface regardless of SDK version).  Griffin /
unified builds for tvOS therefore fail at compile time when the HDR
code paths reference the property, even though the existing gate
accepted any __IPHONE_16_0 || __TVOS_16_0 SDK.

Narrow the compile gate:
  - macOS 11+ SDK:   HDR available (unchanged).
  - iOS 16+ SDK:     HDR available (unchanged).
  - tvOS (any SDK):  HDR unavailable, driver stays in SDR.

Also reword the surrounding comment to match: tvOS is explicitly
excluded because the EDR surface area is not public there, not
because of a missing SDK version.

Author: LibretroAdmin

gfx/drivers/metal.m

@@ -82,30 +82,36 @@
 
 /* HDR availability gate.
  *
- * Compile-time: the SDK must expose CAMetalLayer's wantsExtendedDynamicRangeContent
- * property and the PQ colour space name.  The PQ colour space name
- * (kCGColorSpaceITUR_2100_PQ) is the binding constraint on macOS — it was
- * introduced in 10.15.4 but the symbol is gated to macOS 11.0 in the public
- * headers.  On iOS / tvOS the whole EDR surface area on CAMetalLayer was
- * only exposed in the 16.x SDKs.
+ * Compile-time: the SDK must expose CAMetalLayer's
+ * wantsExtendedDynamicRangeContent property and the PQ colour space name.
+ * The PQ colour space name (kCGColorSpaceITUR_2100_PQ) is the binding
+ * constraint on macOS — introduced in 10.15.4 but gated to macOS 11.0 in
+ * the public headers.  On iOS the EDR surface area on CAMetalLayer was
+ * only exposed in the 16.x SDKs.  tvOS never got a public EDR path:
+ * wantsExtendedDynamicRangeContent / edrMetadata are not part of the
+ * public tvOS interface regardless of SDK version, so HDR is unsupported
+ * there and the driver stays in SDR.
  *
- * We key the compile gate off the Availability.h __MAC_..., __IPHONE_...,
- * __TVOS_... version tokens rather than AvailabilityMacros.h
- * MAC_OS_X_VERSION_* constants: the former are defined consistently across
- * all recent SDKs, while the latter were phased out for newer point releases
- * and checking them fails silently even when the APIs are in fact present.
+ * We key the compile gate off the Availability.h __MAC_... / __IPHONE_...
+ * version tokens rather than AvailabilityMacros.h MAC_OS_X_VERSION_*
+ * constants: the former are defined consistently across all recent SDKs,
+ * while the latter were phased out for newer point releases and checking
+ * them fails silently even when the APIs are in fact present.
  *
  * Runtime: the HDR paths are still guarded with @available(...) checks
- * because RetroArch's Apple deployment targets (macOS 10.13, iOS 11,
- * tvOS 12.1) are lower than the first HDR-capable OS release on each
- * platform.  When the runtime gate is false the driver stays in SDR mode.
+ * because RetroArch's Apple deployment targets (macOS 10.13, iOS 11) are
+ * lower than the first HDR-capable OS release on each platform.  When
+ * the runtime gate is false the driver stays in SDR mode.
  *
  * METAL_HDR_AVAILABLE guards compile-time only. Whenever we touch an HDR-specific
  * API inside those blocks, an @available check guards runtime dispatch. */
 #include <Availability.h>
-#if defined(OSX) && defined(__MAC_11_0)
+#include <TargetConditionals.h>
+#if defined(TARGET_OS_TV) && TARGET_OS_TV
+#  define METAL_HDR_AVAILABLE 0
+#elif defined(OSX) && defined(__MAC_11_0)
 #  define METAL_HDR_AVAILABLE 1
-#elif defined(HAVE_COCOATOUCH) && (defined(__IPHONE_16_0) || defined(__TVOS_16_0))
+#elif defined(HAVE_COCOATOUCH) && defined(__IPHONE_16_0)
 #  define METAL_HDR_AVAILABLE 1
 #else
 #  define METAL_HDR_AVAILABLE 0