clang-format breaks stringify macros with `IndentPPDirectives: AfterHash`

```console
% cat format.c
#if 1
# define __STR(x) #x
#endif

% out/gn/bin/clang-format --style="{BasedOnStyle: llvm, IndentPPDirectives: AfterHash}" format.c 
#if 1
#  define __STR(x) #  x
#endif
```

It shouldn't insert spaces after the `#` in front of `x`.