[clang-format] Correctly handle SpaceBeforeParens for builtins.

That's a partial fix for https://github.com/llvm/llvm-project/issues/55292.

Before, known builtins behaved differently from other identifiers:
```
void f () { return F (__builtin_LINE() + __builtin_FOO ()); }
```
After:
```
void f () { return F (__builtin_LINE () + __builtin_FOO ()); }
```

Reviewed By: owenpan

Differential Revision: https://reviews.llvm.org/D125085