* Reland Clang 11, Roll buildroot to 1bc40a5f916adb93d87e2a2230a0ec43db876c1c (#17457)" (#17464)

This reverts commit 9eacd028.

* Skip more image tests, use newer dsymutil, add missing symbols

Revert "Reland Clang 11, Roll buildroot to 1bc40a5f916adb93d87e2a2230a0ec43db876c1c (#17457)" (#17464)

This reverts commit a4026cc9.

* Reland "Roll Clang to v11, roll buildroot to fe13f79dce4ce9aab3209f11988d825dcf580b4a, allow newly exported symbols (#17440)" (#17451)"

This reverts commit a870bc53.

* skip golden that is different on macos

* buildroot to 1bc40a5f916adb93d87e2a2230a0ec43db876c1c

Started clearing out the semantics information in Dart as well as deleting the AccessibilityBridge. (#17433)

Revert "Roll Clang to v11, roll buildroot to fe13f79dce4ce9aab3209f11988d825dcf580b4a, allow newly exported symbols (#17440)" (#17451)

This reverts commit 8d723aeb.

Roll Clang to v11, roll buildroot to fe13f79dce4ce9aab3209f11988d825dcf580b4a, allow newly exported symbols (#17440)

* Buildroot to fe13f79dce4ce9aab3209f11988d825dcf580b4a

* whitelist more symbols

API staging is complete - these defines have been removed.

Fixes https://github.com/flutter/flutter/issues/18208. All Metal for iOS related work items described in https://github.com/orgs/flutter/projects/5 have been completed.

If the application says there is a new texture but does not provide one, reuse the last texture. (#17437)

This matches the behavior of the OpenGL backend.

We were always scaling z by 0, instead of 1. This
caused the z elevation of some layers to be 0,
which was incorrect.

Now that client apps use the same elevations on
Fuchsia and other platforms, shadows should look
identical.

Matches the structure used on Windows of assuming a directory format.

The following issues have been filed to track the handling of these enum values:

* Handle the UITouchTypeIndirectPointer enum value. https://github.com/flutter/flutter/issues/53696
* Handle the UITouchPhaseRegion enum values. https://github.com/flutter/flutter/issues/53695

No change in functionality. Only makes the iOS engine build on the latest
versions of Xcode and iOS SDK. The enum values cannot be used with the
API_AVAILABLE macro because the buildbots have not been updated yet.

Since the trace provider hasn't been created yet, it is not possible to
trace the creation of a trace provider using a TRACE_DURATION event (the
trace enabled and category check will always fail).  While this isn't
causing any urgent problems, remove it to set a good example for other
clients of tracing that might happen to reference this code.