visionOS: try to pin clang

Author: pblazej

build/patches/pin_clang21.patch

@@ -0,0 +1,13 @@
+diff --git a/toolchain/toolchain.gni b/toolchain/toolchain.gni
+index b92df04ac..1a2b3c4d5 100644
+--- a/toolchain/toolchain.gni
++++ b/toolchain/toolchain.gni
+@@ -43,7 +43,7 @@ declare_args() {
+ }
+
+ declare_args() {
+-  clang_version = "22"
++  clang_version = "21"
+ }
+
+ # Extension for shared library files (including leading dot).

build/run.py

@@ -174,12 +174,16 @@ def get_depot_tools(source_dir, fetch=False):
     'macos_h264_encoder.patch': (2, []),
     'macos_screen_capture.patch': (2, []),
     'macos_use_xcode_clang.patch': (1, ['build']),
+    'pin_clang21.patch': (1, ['build']),
 }
 
 PATCHES = {
-    'apple': [],
+    'apple': [
+        'pin_clang21.patch',
+    ],
     'apple_prefixed': [
         'apple_prefix.patch',
+        'pin_clang21.patch',
     ],
     'windows_x86_64': [
         'add_license_dav1d.patch',