One more!
I needed the below, too.
j2se/src/solaris/native/java/net/Inet6AddressImpl.c
: : : :
#ifndef __GLIBC__
/* gethostname() is in libc.so but I can't find a header file for it */
/***** /usr/include/unistd.h : 407 *******/
extern int gethostname(char *buf, size_t buf_len);
^^^^^^
#endif