Add {get,set}domainname(2)

{get,set}domainname aren't in POSIX but are widely-implemented
extensions.

The Linux kernel provides a setdomainname syscall but not a symmetric
getdomainname syscall, since it expects userspace to get the domain name
from uname(2).

Change-Id: I96726c242f4bb646c130b361688328b0b97269a0
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/libc/Android.mk b/libc/Android.mk
index 828a227..ffa8a27 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -109,6 +109,7 @@
     bionic/ftruncate.cpp \
     bionic/futimens.cpp \
     bionic/getcwd.cpp \
+    bionic/getdomainname.cpp \
     bionic/gethostname.cpp \
     bionic/getpgrp.cpp \
     bionic/getpid.cpp \