Report status when test_runner.cmake completes.

Avoid consuming error messages like "Illegal instruction".

BUG=aomedia:657

Change-Id: Ia7983389ad3519f795f85d0c94a2a3787614a28d

test/test_runner.cmake

@@ -17,4 +17,6 @@ endif ()
 
 set($ENV{GTEST_SHARD_INDEX} ${GTEST_SHARD_INDEX})
 set($ENV{GTEST_TOTAL_SHARDS} ${GTEST_TOTAL_SHARDS})
-execute_process(COMMAND ${TEST_LIBAOM})
+execute_process(COMMAND ${TEST_LIBAOM} RESULT_VARIABLE test_result)
+set(test_message "Test shard ${GTEST_SHARD_INDEX}/${GTEST_TOTAL_SHARDS} result")
+message("${test_message}: ${test_result}")