common_audio/signal_processing: Remove macro WEBRTC_SPL_MEMCPY_W8 This macro is nothing but memcpy() and further used at one single place in webrtc, so it makes no sense to keep it. Replaced the operation where it is used. BUG=3348,3353 TESTED=locally on linux TBR=aluebs@webrtc.org Review URL: https://webrtc-codereview.appspot.com/18259004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@6963 4adac7df-926f-26a2-2b94-8c16560cd09d