Move the aec_rdft* files to a more proper place beneath APM and make them thread-safe.

webrtc/modules/audio_processing/utility/ooura_fft.h

+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.

[hlundin-webrtc, 2016/10/05 12:54:53]

Is this new or old? Should it be 2011 or 2016?

[peah-webrtc, 2016/10/06 06:23:39]

This is basically what remained when the former include file was edited. It is
actually the former renamed include file, but since it is almost totally changed
I think a data change should be motivated. I'll change that. Please let me know,
though, if you think otherwise.

Done.

[hlundin-webrtc, 2016/10/06 08:48:44]

If some significant part of the old file remains in the new, I think the old
year should be used. But if it is only trivial parts (like the copyright notice)
that remains, then stamp it 2016.

[peah-webrtc, 2016/10/06 12:41:44]

Acknowledged.

+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_OOURA_FFT_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_OOURA_FFT_H_
+
+#include "webrtc/typedefs.h"
+
+namespace webrtc {
+
+#if defined(WEBRTC_ARCH_X86_FAMILY)
+void cft1st_128_SSE2(float* a);
+void cftmdl_128_SSE2(float* a);
+void rftfsub_128_SSE2(float* a);
+void rftbsub_128_SSE2(float* a);
+#endif
+
+#if defined(MIPS_FPU_LE)
+void cft1st_128_mips(float* a);
+void cftmdl_128_mips(float* a);
+void rftfsub_128_mips(float* a);
+void rftbsub_128_mips(float* a);
+#endif
+
+#if defined(WEBRTC_HAS_NEON)
+void cft1st_128_neon(float* a);
+void cftmdl_128_neon(float* a);
+void rftfsub_128_neon(float* a);
+void rftbsub_128_neon(float* a);
+#endif
+
+class OouraFft {
+ public:
+  OouraFft();
+  ~OouraFft();
+  void Fft(float* a) const;
+  void InverseFft(float* a) const;
+
+ private:
+  void cft1st_128(float* a) const;
+  void cftmdl_128(float* a) const;
+  void rftfsub_128(float* a) const;
+  void rftbsub_128(float* a) const;
+
+  void cftfsub_128(float* a) const;
+  void cftbsub_128(float* a) const;
+  void bitrv2_128(float* a) const;
+  bool use_sse2_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_OOURA_FFT_H_