[Fontconfig] Wrong Documented Type For FC_LANG?

[Lawrence D'Oliveiro]

In fontconfig.h, the “lang” property is listed as follows:

    #define FC_LANG		    "lang"		/* String RFC 3066 langs */

this would seem to indicate that the value is supposed to be a
string. I just discovered, in running a test with my python_fontconfig
binding <https://github.com/ldo/python_fontconfig/>, that in fact this
property value is an FcLangSet.

Does this apply to the other properties with “lang” in their name as
well?