Remove Opus from DEPS and import a local copy

third_party/opus/src/celt/arm/fixed_arm64.h

Index: third_party/opus/src/celt/arm/fixed_arm64.h
diff --git a/third_party/opus/src/celt/arm/fixed_arm64.h b/third_party/opus/src/celt/arm/fixed_arm64.h
new file mode 100644
index 0000000000000000000000000000000000000000..c6fbd3db2c17dd6d1916158e1cb3db328bd2ece5
--- /dev/null
+++ b/third_party/opus/src/celt/arm/fixed_arm64.h
@@ -0,0 +1,35 @@
+/* Copyright (C) 2015 Vidyo */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef FIXED_ARM64_H
+#define FIXED_ARM64_H
+
+#include <arm_neon.h>
+
+#undef SIG2WORD16
+#define SIG2WORD16(x) (vqmovns_s32(PSHR32((x), SIG_SHIFT)))
+
+#endif