[Opus] Update to v1.2.1

third_party/opus/src/doc/Doxyfile.in

Index: third_party/opus/src/doc/Doxyfile.in
diff --git a/third_party/opus/src/doc/Doxyfile.in b/third_party/opus/src/doc/Doxyfile.in
index cd776752d4967dde618f900727d6705e5dc87a0f..36eee0b5380b80432796310267852cb162a46bd1 100644
--- a/third_party/opus/src/doc/Doxyfile.in
+++ b/third_party/opus/src/doc/Doxyfile.in
@@ -318,3 +318,18 @@ PREDEFINED             = OPUS_EXPORT= \
                          OPUS_CUSTOM_EXPORT_STATIC= \
                          OPUS_WARN_UNUSED_RESULT= \
                          OPUS_ARG_NONNULL(_x)=
+
+#---------------------------------------------------------------------------
+# Configuration options related to the dot tool
+#---------------------------------------------------------------------------
+
+# If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
+# available from the path. This tool is part of Graphviz (see:
+# http://www.graphviz.org/), a graph visualization toolkit from AT&T and Lucent
+# Bell Labs.
+
+# Debian defaults to YES here, while Fedora and Homebrew default to NO.
+# So we set this based on whether the graphviz package is available at
+# configure time.
+#
+HAVE_DOT = @HAVE_DOT@