[travis] Add .travis/after_failure

.travis.yml

@@ -48,3 +48,4 @@ before_install:
 
 script: ./.travis/build
 after_success: ./.travis/after_success
+after_failure: ./.travis/after_failure

.travis/after_failure

+#!/bin/bash
+
+# Set debug mode
+set -x
+set -v
+
+# Display post-failure environment
+echo "Environment:"
+env
+
+# Dump as much log as we can
+find $build_dir -name "*.log" | xargs cat
+
+# End debug mode
+set +v
+set +x