Add indentation rule for definterface (#395)

Author: Ben Sima

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Bugs fixed
 
+* Fixed indentation of `definterface` to match that of `defprotocol`.
 * [#389](https://github.com/clojure-emacs/clojure-mode/issues/389): Fixed the indentation of `defrecord` and `deftype` multiple airity protocol forms.
 
 ## 5.5.0 (2016-06-25)

clojure-mode.el

@@ -1316,6 +1316,7 @@ work).  To set it from Lisp code, use
   (deftype '(2 nil nil (:defn)))
   (defrecord '(2 nil nil (:defn)))
   (defprotocol '(1 (:defn)))
+  (definterface '(1 (:defn)))
   (extend 1)
   (extend-protocol '(1 :defn))
   (extend-type '(1 :defn))

test/clojure-mode-indentation-test.el

@@ -297,6 +297,15 @@ values of customisable variables."
     [this]
     \"Why is this over here?\"))")
 
+
+(def-full-indent-test definterface
+  "(definterface IFoo
+  (foo [this]
+    \"Why is this over here?\")
+  (foo-2
+    [this]
+    \"Why is this over here?\"))")
+
 (def-full-indent-test specify
   "(specify obj
   ISwap