NFC: use visionOS instead of xrOS in the Swift codebase. We can't do

much about the LLVM triple, but we can do our best on the Swift side.

Author: rjmccall

include/swift/AST/RuntimeVersions.def

@@ -135,7 +135,7 @@ RUNTIME_VERSION(
   PLATFORM(macOS,   (14, 4, 0))
   PLATFORM(iOS,     (17, 4, 0))
   PLATFORM(watchOS, (10, 4, 0))
-  PLATFORM(xrOS, (1, 0, 0))
+  PLATFORM(visionOS,(1, 0, 0))
 )
 
 END_MAJOR_VERSION(5)
@@ -147,7 +147,7 @@ RUNTIME_VERSION(
   PLATFORM(macOS,   (15, 0, 0))
   PLATFORM(iOS,     (18, 0, 0))
   PLATFORM(watchOS, (11, 0, 0))
-  PLATFORM(xrOS, (2, 0, 0))
+  PLATFORM(visionOS,(2, 0, 0))
 )
 
 RUNTIME_VERSION(

lib/AST/Availability.cpp

@@ -877,7 +877,7 @@ AvailabilityRange ASTContext::getSwiftAvailability(unsigned major,
 #define PLATFORM_TEST_macOS     target.isMacOSX()
 #define PLATFORM_TEST_iOS       target.isiOS()
 #define PLATFORM_TEST_watchOS   target.isWatchOS()
-#define PLATFORM_TEST_xrOS      target.isXROS()
+#define PLATFORM_TEST_visionOS  target.isXROS()
 
 #define _SECOND(A, B) B
 #define SECOND(T) _SECOND T
@@ -892,7 +892,7 @@ AvailabilityRange ASTContext::getSwiftAvailability(unsigned major,
 #undef PLATFORM_TEST_macOS
 #undef PLATFORM_TEST_iOS
 #undef PLATFORM_TEST_watchOS
-#undef PLATFORM_TEST_xrOS
+#undef PLATFORM_TEST_visionOS
 #undef _SECOND
 #undef SECOND