libidn 2.0.6 mingw build fails

[Ray Satiro]

missing strchrnul and strverscmp

Creating library file: .libs/libidn2.dll.a.libs/lookup.o: In function 
`idn2_lookup_u8':
c:\wget\rootarchives\libidn2-0.6/lookup.c:134: undefined reference to 
`strchrnul'
.libs/version.o: In function `idn2_check_version':
c:\wget\rootarchives\libidn2-0.6/version.c:44: undefined reference to 
`strverscmp
'
collect2: ld returned 1 exit status
make[2]: *** [libidn2.la] Error 1
make[2]: Leaving directory `/c/wget/rootarchives/libidn2-0.6'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/c/wget/rootarchives/libidn2-0.6'
make: *** [all] Error 2