iOS toolchain: Pass IOS_APP_STORE to CMake's compiler checks

They re-read the toolchain file without the cache, so they used the non-App
Store deployment target, which current Xcode no longer supports.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmake/Toolchains/ios.cmake

@@ -12,6 +12,8 @@
 # PPSSPP platform flags
 set(MOBILE_DEVICE ON)
 set(USING_GLES2 ON)
+# The compiler checks re-read this file without the cache, so pass IOS_APP_STORE on.
+list(APPEND CMAKE_TRY_COMPILE_PLATFORM_VARIABLES IOS_APP_STORE)
 if(IOS_APP_STORE)
   # The static MoltenVK in ios/MoltenVK needs 15.0.
   set(IPHONEOS_DEPLOYMENT_TARGET 15.0)