Only build multithreaded functions on mt builds.

Change-Id: I2e0cc72a0543bfea1d2d3499b9906519d5cb3f15

vp8/encoder/bitstream.c

diff --git a/vp8/encoder/bitstream.c b/vp8/encoder/bitstream.c
index ea279b3..f3d91b5 100644
--- a/vp8/encoder/bitstream.c
+++ b/vp8/encoder/bitstream.c
@@ -407,6 +407,7 @@
 }
 
 
+#if CONFIG_MULTITHREAD
 static void pack_mb_row_tokens(VP8_COMP *cpi, vp8_writer *w)
 {
     int mb_row;
@@ -421,6 +422,7 @@
     }
 
 }
+#endif  // CONFIG_MULTITHREAD
 
 static void write_mv_ref
 (
@@ -1675,7 +1677,7 @@
         if (cpi->b_multi_threaded)
             pack_mb_row_tokens(cpi, &cpi->bc[1]);
         else
-#endif
+#endif  // CONFIG_MULTITHREAD
             vp8_pack_tokens(&cpi->bc[1], cpi->tok, cpi->tok_count);
 
         vp8_stop_encode(&cpi->bc[1]);

vp8/encoder/encodeframe.c

diff --git a/vp8/encoder/encodeframe.c b/vp8/encoder/encodeframe.c
index d381d8d..b0aaa2f 100644
--- a/vp8/encoder/encodeframe.c
+++ b/vp8/encoder/encodeframe.c
@@ -700,6 +700,7 @@
     vp8_zero(x->count_mb_ref_frame_usage);
 }
 
+#if CONFIG_MULTITHREAD
 static void sum_coef_counts(MACROBLOCK *x, MACROBLOCK *x_thread)
 {
     int i = 0;
@@ -729,6 +730,7 @@
     }
     while (++i < BLOCK_TYPES);
 }
+#endif  // CONFIG_MULTITHREAD
 
 void vp8_encode_frame(VP8_COMP *cpi)
 {
@@ -927,7 +929,7 @@
 
         }
         else
-#endif
+#endif  // CONFIG_MULTITHREAD
         {
 
             /* for each macroblock row in image */