Include files from webrtc/.. paths in common_audio/

BUG=1662
R=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1535005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4107 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/common_audio/signal_processing/downsample_fast.c b/webrtc/common_audio/signal_processing/downsample_fast.c
index 4784aba..179c36a 100644
--- a/webrtc/common_audio/signal_processing/downsample_fast.c
+++ b/webrtc/common_audio/signal_processing/downsample_fast.c
@@ -8,7 +8,7 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "signal_processing_library.h"
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
 
 // TODO(Bjornv): Change the function parameter order to WebRTC code style.
 // C version of WebRtcSpl_DownsampleFast() for generic platforms.