Compile delta_generator for the host.

Bug: 24619596
TEST=mma on linux.

Change-Id: Icccae2b938b4fdd698b177beee96ffb62e9f63ae
diff --git a/update_engine.gyp b/update_engine.gyp
index b40d5b3..97ed4c2 100644
--- a/update_engine.gyp
+++ b/update_engine.gyp
@@ -292,6 +292,7 @@
       'variables': {
         'exported_deps': [
           'libupdate_engine-client',
+          'dbus-1',
         ],
         'deps': ['<@(exported_deps)'],
       },