locale.c: Fix conditional compilation

locale.c: Fix conditional compilation

With Perl 5.28.0, there are some mismatches between blocks
and conditional compilation in the Perl__is_cur_LC_category_utf8() function.
The compilation of miniperl could fails like this:
```
locale.c: In function `Perl__is_cur_LC_category_utf8`:
locale.c:5481:1: error: expected declaration or statement at end of input
 }
 ^
```

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>