Remove broxygen Sphinx integration

The broxygen-generated files now live in the git repo, have tests
that check that they are up-to-date, and a script to re-generate
them on-demand.

testing/btest/coverage/sphinx-broxygen-docs.sh

@@ -0,0 +1,33 @@
+# This script checks whether the reST docs generated by broxygen are stale.
+# If this test fails, then simply run:
+#
+#     testing/scripts/gen-broxygen-docs.sh
+#
+#  and then include the changes in your commit.
+#
+# @TEST-EXEC: bash $SCRIPTS/gen-broxygen-docs.sh ./doc
+# @TEST-EXEC: bash %INPUT
+
+function check_diff
+    {
+    local file=$1
+    echo "Checking $file for differences"
+    diff -Nru $file $DIST/$file 1>&2
+
+    if [ $? -ne 0 ]; then
+        echo "============================" 1>&2
+        echo "$DIST/$file is outdated" 1>&2
+        echo "Re-run the following command:" 1>&2
+        echo "" 1>&2
+        echo "    $SCRIPTS/gen-broxygen-docs.sh" 1>&2
+        echo "" 1>&2
+        echo "And then include the changes in your commit" 1>&2
+        exit 1
+    fi
+    }
+
+for file in $(find ./doc -name autogenerated-*); do
+    check_diff $file
+done
+
+check_diff ./doc/scripts