Improve StreamTest error message

Bug: 134732760
Change-Id: If703d2593129b418ae54f90bd018d09f2f548bb7

src/test/java/com/android/tools/r8/desugar/corelib/corelibjdktests/Jdk11StreamTests.java

diff --git a/src/test/java/com/android/tools/r8/desugar/corelib/corelibjdktests/Jdk11StreamTests.java b/src/test/java/com/android/tools/r8/desugar/corelib/corelibjdktests/Jdk11StreamTests.java
index 7816986..d900dea 100644
--- a/src/test/java/com/android/tools/r8/desugar/corelib/corelibjdktests/Jdk11StreamTests.java
+++ b/src/test/java/com/android/tools/r8/desugar/corelib/corelibjdktests/Jdk11StreamTests.java
@@ -247,7 +247,11 @@
           // TODO(b/134732760): Investigate and fix these issues.
           numHardFailures++;
         } else {
-          fail();
+          String errorMessage = "STDOUT:\n"+
+              result.getStdOut()
+              + "STDERR:\n" +
+              result.getStdErr();
+          fail(errorMessage);
         }
       }
     }