macOS 27 release candidate breaks linking (arm64e.x1 - "unknown architecture")

### Solution to issue cannot be found in the documentation.

- [x] I checked the documentation.

### Issue

Looks like the latest macOS 27 (release candidate) command line tools introduced a new `arm64e.x1` architecture, linking fails:

```
❯ cc test.c -o t
ld: warning: ignoring file /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd, malformed file
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd:4:20: error: unknown architecture
arm64e.x1-macos, arm64e.x1-maccatalyst ]
^~~~~~~~~~~~~~~

ld: dynamic executables or dylibs must link with libSystem.dylib for architecture arm64
cc: error: linker command failed with exit code 1 (use -v to see invocation)
```

```
❯ head /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd
--- !tapi-tbd
tbd-version: 4
targets: [ x86_64-macos, x86_64-maccatalyst, arm64e-macos, arm64e-maccatalyst,
arm64e.x1-macos, arm64e.x1-maccatalyst ]
```

Seems to be similar to https://github.com/conda-forge/tapi-feedstock/issues/16

### Installed packages

```shell
❯ pkgutil --pkg-info=com.apple.pkg.CLTools_Executables
package-id: com.apple.pkg.CLTools_Executables
version: 27.0.0.0.1788430756
```

### Environment info

```shell
-
```

Start by reproducing the failure with `cc test.c -o t` using macOS 27 Command Line Tools 27.0.0.0.1788430756, then inspect the tapi-feedstock recipe and its handling of `libSystem.tbd` targets. Done means the reported arm64e.x1 targets no longer cause the linker to reject the SDK, with the reproduction command succeeding.

Written by the indexing model from the issue text.