Merge branch 'sg/travis-osx-brew-breakage-workaround'

The way the OSX build jobs updates its build environment used the
"--quiet" option to "brew update" command, but it wasn't all that
quiet to be useful.  The use of the option has been replaced with
an explicit redirection to the /dev/null (which incidentally would
have worked around a breakage by recent updates to homebrew, which
has fixed itself already).

* sg/travis-osx-brew-breakage-workaround:
  travis-ci: make the OSX build jobs' 'brew update' more quiet

ci/install-dependencies.sh

@@ -34,7 +34,7 @@ linux-clang|linux-gcc)
 	popd
 	;;
 osx-clang|osx-gcc)
-	brew update --quiet
+	brew update >/dev/null
 	# Uncomment this if you want to run perf tests:
 	# brew install gnu-time
 	test -z "$BREW_INSTALL_PACKAGES" ||