brew install workarounds on Travis

'brew install guile' does not complete within 10 minutes and the build is then killed by Travis
Suggestion and original script from travis-ci/travis-ci#1961

Tools/brew-install

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Wrapper around 'brew install' emitting a message every minute if the command is still running.
+# This is used on Travis to ensure the install isn't killed when there is no output over a long period (10 minutes).
+# Usage: brew-install package, where package is the name of the package for brew to install.
+
+seconds=0
+minutes=0
+brew install $1 &
+while true; do
+  ps -p$! 2>& 1>/dev/null
+  if [ $? = 0 ]; then
+    if [ $seconds = 60 ]; then
+      let seconds=0
+      let minutes=minutes+1
+      echo "brew install $1 still running ($minutes min)"
+    fi
+    sleep 1
+    let seconds=seconds+1
+  else
+    break
+  fi
+done
+wait $!
+exit $?