Add Enchant to build dependencies.

INSTALL

@@ -46,6 +46,7 @@
       * sqlite3
       * webkitgtk-3.0
       * gcr-3
+      * enchant
       * messaging-menu (optional; enables support for Ubuntu Unity messaging
         menu)
       * unity (optional; enables support for Ubuntu Unity launcher)
@@ -63,7 +64,7 @@
             desktop-file-utils gnome-doc-utils libcanberra-devel libgee-devel \
             glib2-devel gmime-devel gtk3-devel libnotify-devel sqlite-devel \
             unique3-devel webkitgtk3-devel libsecret-devel libxml2-devel \
-            vala-tools gcr-devel
+            vala-tools gcr-devel enchant-devel
 
 
   * Installing dependencies on Ubuntu/Debian
@@ -77,7 +78,7 @@
             libgee-0.8-dev libglib2.0-dev libgmime-2.6-dev libgtk-3-dev \
             libsecret-1-dev libxml2-dev libnotify-dev libsqlite3-dev \
             libunique-3.0-dev libwebkitgtk-3.0-dev libmessaging-menu-dev \
-            libunity-dev libgcr-3-dev
+            libunity-dev libgcr-3-dev libenchant-dev
 
     Ubuntu 14.04 (Trusty LTS) and 12.04 (Precise LTS) do not have all
     the dependencies to build Geary.  See