Enable vpxenc to specify internal coded frame size

Added command line flags "resize-width" & "resize-height"
to allow the user to specify the frame size to encode at.

These two flags are ignored if the "resize-allowed" switch
is not set to 1.

All frames in the clip are then encoded at this size, which
must be smaller than the raw frame size.

Change-Id: I3d64bd9303d5c0bd678461a866a1ea621700d744
diff --git a/vp8/vp8_cx_iface.c b/vp8/vp8_cx_iface.c
index 4c896b1..6ca6087 100644
--- a/vp8/vp8_cx_iface.c
+++ b/vp8/vp8_cx_iface.c
@@ -1235,6 +1235,8 @@
 
         0,                  /* rc_dropframe_thresh */
         0,                  /* rc_resize_allowed */
+        1,                  /* rc_scaled_width */
+        1,                  /* rc_scaled_height */
         60,                 /* rc_resize_down_thresold */
         30,                 /* rc_resize_up_thresold */