Opus: Fixes a surround bug on loud signal

Backport patch released in v1.1.5
https://git.xiph.org/?p=opus.git;a=commitdiff;h=8d02afe05b80097f5a09361bb75e2950cb3ea6e2

BUG=728233

Review-Url: https://codereview.chromium.org/2918573003
Cr-Commit-Position: refs/heads/master@{#476384}

third_party/opus/README.chromium

@@ -18,3 +18,4 @@ Local changes:
   https://git.xiph.org/?p=opus.git;a=commit;h=79e8f527b0344b0897a65be35e77f7885bd99409
   https://git.xiph.org/?p=opus.git;a=commitdiff;h=e5ad26169502c1f0b067916e782c2b3fdea6fba9
   https://git.xiph.org/?p=opus.git;a=commitdiff;h=5da0498a3e23339aaceba659a97e935031d5693d
+  https://git.xiph.org/?p=opus.git;a=commitdiff;h=8d02afe05b80097f5a09361bb75e2950cb3ea6e2

third_party/opus/src/src/opus_multistream_encoder.c

@@ -277,7 +277,7 @@ void surround_analysis(const CELTMode *celt_mode, const void *pcm, opus_val16 *b
          sum = celt_inner_prod(in, in, frame_size+overlap, 0);
          /* This should filter out both NaNs and ridiculous signals that could
             cause NaNs further down. */
-         if (!(sum < 1e9f) || celt_isnan(sum))
+         if (!(sum < 1e18f) || celt_isnan(sum))
          {
             OPUS_CLEAR(in, frame_size+overlap);
             preemph_mem[c] = 0;