travis.ci: enable ctest_output_on_failure

gcontini

2020-04-26 b01f4512ae3aa25426cb84758a791478ab68d5d7

 src/library/base/CMakeLists.txt

@@ -3,7 +3,7 @@
    StringUtils.cpp
    file_utils.cpp
    base64.cpp
    logger.c
    logger.cpp
)

if(CODE_COVERAGE AND UNIX)