THRIFT-3110 Print error log after cross test failures on Travis

 This closes #458

 commit 7dfc994028df512d791f79c090d3d6cc1108a815
 Author: Nobuaki Sukegawa <nsukeg@gmail.com>
 Date: 2015-04-23T16:38:55Z
diff --git a/.travis.yml b/.travis.yml
index e5b8e02..b49c0a3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,6 +44,9 @@
   - if [ "x$CONFIG" != "xnone" ] ; then sh configure $CONFIG ; fi
   - if [ "x$CONFIG" != "xnone" ] ; then make $MAKE_TARGET -j2 ; fi
 
+after_failure:
+  - if [ "x$ERROR_LOG" != "xnone" ] ; then cat $ERROR_LOG ; fi
+
 env:
   global:
     - TEST_NAME=""
@@ -60,6 +63,7 @@
       CONFIG="--enable-tutorial=no --without-erlang --without-lua --without-haxe --without-d"
       ALL_DEPS="yes"
       MAKE_TARGET="cross"
+      ERROR_LOG="test/log/unexpected_failures.log"
 
     # CMake builds
     - TEST_NAME="compiler (CMake + CPack)"