> In file included from htscore.c:49: 
> htsnet.h:153: field `in6' has incomplete type

struct sockaddr_in6 is not defined?!
Then, add the ac_cv_lib_c_getaddrinfo=0 option to the 
configure call:

./configure ac_cv_lib_c_getaddrinfo=0
make CFLAGS="-DNOSTRDEBUG"
make install

This should work this time!