Update run_distrib_test_cmake.sh

test/distrib/cpp/run_distrib_test_cmake.sh

@@ -24,7 +24,8 @@ apt-get update
 apt-get install -t jessie-backports -y libssl-dev
 
 # Install c-ares
-# This section can be replaced with:
+# If the distribution provides a new-enough version of c-ares,
+# this section can be replaced with:
 # apt-get install -y libc-ares-dev
 mkdir -p "third_party/cares/cares/cmake/build"
 pushd "third_party/cares/cares/cmake/build"