reverted an accidental code deleting

commit cf561bad accidentally deleted a line of code that sets the
base_qindex for each frame, which leads to every frame is encoded
at Q of 0.

Change-Id: Ib5f8022e856bf3b3bd0d4147405e46241e3dcf2d

vp8/encoder/quantize.c

@@ -1272,6 +1272,8 @@ void vp8_set_quantizer(struct VP8_COMP *cpi, int Q)
 {
     VP8_COMMON *cm = &cpi->common;
 
+    cm->base_qindex = Q;
+
     // if any of the delta_q values are changing update flag will
     // have to be set.
     cm->y1dc_delta_q = 0;