gnu: Rename module dnsmasq to dns.

* gnu/packages/dnsmasq.scm: Rename to...
* gnu/packages/dns.scm: ... this.  Change module name accordingly.
* gnu-system.am (GNU_SYSTEM_MODULES): Rename dnsmasq module to dns.

gnu-system.am

@@ -81,7 +81,7 @@ GNU_SYSTEM_MODULES =				\
   gnu/packages/dictionaries.scm			\
   gnu/packages/disk.scm				\
   gnu/packages/djvu.scm				\
-  gnu/packages/dnsmasq.scm			\
+  gnu/packages/dns.scm				\
   gnu/packages/docbook.scm			\
   gnu/packages/doxygen.scm			\
   gnu/packages/dwm.scm				\

gnu/packages/dns.scm

@@ -16,7 +16,7 @@
 ;;; You should have received a copy of the GNU General Public License
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
-(define-module (gnu packages dnsmasq)
+(define-module (gnu packages dns)
   #:use-module (guix licenses)
   #:use-module (guix packages)
   #:use-module (guix download)