[compiler-rt][asan] Reland: wcscpy/wcsncpy interceptors and stabilize wchar tests on Darwin/Android (#162028)

### Summary
Reland: wcscpy/wcsncpy interceptors and stabilize wchar tests on
Darwin/Android. Functional reland (runtime + tests).

### Context
Reland of #160493 and #161624; previously reverted by #162021 and
#162001 to restore green.

### Motivation
- Restore wchar interceptors (wcscpy/wcsncpy), broaden ASan coverage,
and improve Windows parity with narrow-string checks.
- Make tests robust across Darwin/Android to keep bots green.

### Runtime (wcscpy/wcsncpy)
- Add overlap checks; mark read/write ranges in bytes.
- Use MaybeRealWcsnlen when available to bound reads.
- Register Windows static runtime thunk where applicable.

### Tests (wcscpy/wcsncpy/wcscat/wcsncat)
- Android: keep `%env_asan_opts=log_to_stderr=1` so the ASan header is
on stderr.
- Darwin: tolerate reordering by putting all four key lines in one DAG
group:

```cpp
// CHECK-DAG: Good so far.
// CHECK-DAG: ERROR: AddressSanitizer: stack-buffer-overflow on address [[ADDR:...]] at pc {{...}} bp {{...}} sp {{...}}
// CHECK-DAG: WRITE of size {{[0-9]+}} at [[ADDR]] thread T0
// CHECK-DAG: #0 {{0x[0-9a-f]+}} in <func>
```

### Risk
- Functional reland (runtime + tests), intended to restore functionality
and maintain stability across platforms.

---------

Signed-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>

0 files changed, 0 insertions, 0 deletions