When I did a fresh build of ports, I got this while building fontconfig:
```
checking for FREETYPE... no
configure: error: Package requirements (freetype2 >= 21.0.15) were not
met:
No package 'freetype2' found
Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.
Alternatively, you may set the environment variables FREETYPE_CFLAGS
and FREETYPE_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
```
All of these patches did the same thing, which is already in upstream
config.sub.
With this change, we need only add `use_fresh_config_sub=true` to
the package.sh file.
Note that this is not done automatically in case the port has a modified
config.sub file.
