Log Message:
glib2: fix build on sunos.

- Default to a newer POSIX, since we build this package with -std=gnu99
- Link against libnsl and libintl
- Don't use mnt_opt
  - XXX who else uses this case in gunixmounts.c?
- include <sys/filio.h> for FIONREAD.
- Auto-detect GNU iconv.
- Don't fail if getxattr is not available. The code is already ready
  for this case with some small configure changes.