[compiler-rt][CFI] Allow -fno-rtti libunwind vtables in normalize-integers-wpd.cpp (#242605)

Fixes forward #242466 -- in toolchains that link static libc++,
libc++abi, and libunwind, the libunwind link pulls in internal vtables
without `_ZTI` symbols, which suppresses the expected WPD transform.

Mark these vtables as safe with flags so they _don't_ disable WPD and
the test continues to be effective.

Assisted-by: Antigravity with Gemini
GitOrigin-RevId: 96c8c412b2aa4ed9ac289f525ba3720eb08df024