EntryExitInstrumenter: skip naked functions

The asm in a naked function may reasonably expect the argument registers and the
return address register (if present) to be live.

When using -pg and -finstrument-functions, functions are instrumented by adding
a function call to `_mcount/__cyg_profile_func_enter/__cyg_profile_func_enter_bare`/etc,
which will clobber these registers. If the return address register is clobbered,
the function will be unable to return to the caller, possibly causing an
infinite loop.

```
__attribute__((naked)) void g() {
#if defined(__arm__)
  __asm__("bx lr");
#else
  __asm__("ret");
#endif
}

int main() { g(); }
```

It seems that the only one reasonable way to handle the combination is to
disable instrumenting for naked functions.

GCC PR: https://gcc.gnu.org/PR109707
Close https://github.com/llvm/llvm-project/issues/62504

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D149721