[llvm] Remove iOS 5 check for tailcalls on ARM (PR #133354)

[via llvm-commits]

Un1q32 wrote:

I did a quick test with dyld and it seems to work.  Just a main function that tail calls to a function in a dylib.

test.dylib:
```c
int func(void) {
    return 42;
}
```

a.out:
```c
extern int func(void);

int main(void) {
    return func();
}
```

https://github.com/llvm/llvm-project/pull/133354