Fix array declarations in aec_core.c

Was causing warnings in Chromium such as:

warning C4742: 'WebRtcAec_overDriveCurve' has different alignment in 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core_sse2.c' and 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core.c': 4 and 16
warning C4744: 'WebRtcAec_overDriveCurve' has different type in 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core_sse2.c' and 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core.c': 'array (260 bytes)' and '__declspec(align(16)) array (260 bytes)'
warning C4742: 'WebRtcAec_weightCurve' has different alignment in 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core_sse2.c' and 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core.c': 4 and 16
warning C4744: 'WebRtcAec_weightCurve' has different type in 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core_sse2.c' and 'E:\src\buildbot\build\slave\fake_slave\build\src\third_party\webrtc\modules\audio_processing\aec\aec_core.c': 'array (260 bytes)' and '__declspec(align(16)) array (260 bytes)'

BUG=https://code.google.com/p/chromium/issues/detail?id=336620
R=andrew@webrtc.org, cd@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/15869004

Patch from Sebastien Marchand <sebmarchand@chromium.org>.

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6525 4adac7df-926f-26a2-2b94-8c16560cd09d