warning: "_GL_ATTRIBUTE_DEALLOC_FREE" redefined

[Werner LEMBERG]

[66c5e7dd3aa58bde7a928867a763bf7e11206c93]

Without changing my source code (https://repo.or.cz/ttfautohint.git)
or the compiler (gcc 7.5.0), an update of gnulib from 2021-08-07 to
2021-01-13 suddenly produces a bunch of new, identical warnings on my
openSUSE Leap 15.2 GNU/Linux box, which look like the following.

```
  CC       lib/libttfautohint_la-tafeature.lo
In file included from lib/ta.h:19:0,
                 from lib/tashaper.h:31,
                 from lib/tafeature.c:15:
./config.h:842:0: warning: "_GL_ATTRIBUTE_DEALLOC_FREE" redefined
 #define _GL_ATTRIBUTE_DEALLOC_FREE _GL_ATTRIBUTE_DEALLOC (free, 1)
 
In file included from 
/usr/local/include/freetype2/freetype/config/ftstdlib.h:88:0,
                 from 
/usr/local/include/freetype2/freetype/config/ftconfig.h:41,
                 from /usr/local/include/freetype2/freetype/freetype.h:24,
                 from lib/tashaper.h:25,
                 from lib/tafeature.c:15:
./gnulib/src/string.h:630:0: note: this is the location of the previous 
definition
 #  define _GL_ATTRIBUTE_DEALLOC_FREE _GL_ATTRIBUTE_DEALLOC (rpl_free, 1)
```

How can I make them disappear?


    Werner