Fix array declarations in aec_rdft.h.

Was causing warnings in Chromium such as:
warning C4742: 'rdft_wk2i' has different alignment in
'webrtc\modules\audio_processing\aec\aec_rdft_sse2.c' and
'webrtc\modules\audio_processing\aec\aec_rdft.c': 4 and 16

BUG=chromium:336620
R=cduvivier@google.com

Review URL: https://webrtc-codereview.appspot.com/7489004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5419 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed