[golang/go] cmd/internal/testdir: Test/fixedbugs/{issue42032,issue51733,issue40954}.go fail with "missing LC_UUID load command" on macOS 26 in Go 1.25

### ROOT CAUSE The test cases in `Test/fixedbugs/{issue42032,issue51733,issue40954}.go` are failing on macOS because they expect the `LC_UUID` load command to be present in the Mach-O binary, but the Go compiler does not generate it in certain build modes (e.g., `buildmode=exe`). This is due to the fact that the `buildid` package, which handles the generation of `LC_UUID`, is not used in the `exe` build mode. The tests likely rely on the presence of `LC_UUID` for validation, but the Go compiler does not include it in `exe` mode. ### CODE FIX Modify the tests to use the standard build mode (which includes the `buildid` package and generates `LC_UUID`) instead of `buildmode=exe`. Here's how to update the test: 1. **Identify the build mode**: Check if the test uses `-buildmode=exe` or any other custom build mode. If so, change it to the default build mode. 2. **Update the test code**: Replace any `-buildmode=exe` flags with the default build mode (which is typically `internal` or the standard mode). For example, change: ```go // Incorrect: Using buildmode=exe _, err := build.Exec(..., build.BuildmodeBuildmodeexe...) ``` to ```go // Correct: Use default build mode (no buildmode specified) _, err := build.Exec(...) ``` 3. **Re-run the tests**: After removing the `-buildmode=exe` flag, the tests should pass because the Go compiler will now generate the `LC_UUID` load command. This change ensures that the binaries created by the tests include the `LC_UUID` load command, aligning with the expected behavior for the test cases.