Add idn2 tool, configure for Darwin.
- wchar.h: contrib/libs/libunistring/wchar.h
- wctype.h: contrib/libs/libunistring/wctype.h
+- source_filter: "^contrib/libs/libidn2/"
+ includes:
+ - error.h: contrib/libs/libidn2/gl/error.h
+ - unistd.h: contrib/libs/libunistring/include/unistd.h
+
# Same as libunistring - lftp has own libc header wrappers/replacements.
# However here we have GLOBAL ADDINCL to contrib/libs/lftp{,/trio,/lib}
# that can poison resolving in PEERDIRing projects.
