It seems the test suite on s390x failed, and at least this error is
visible in the log:
g++ -o .sconf_temp/conftest_7.o -c -Wno-long-long -Wno-deprecated
-ansi -pipe -g -O3 -DNDEBUG -mzarch -march=z196 -mtune=zEC12 -Wall
-Wextra -Wno-unused-parameter -D_FORTIFY_SOURCE=2 -pthread
-D_XOPEN_SOURCE=600 -DHAVE_COMMON_H -DGALERA_USE_GU_NETWORK
-DHAVE_BYTESWAP_H -DHAVE_ENDIAN_H -DHAVE_BOOST_SHARED_PTR_HPP
.sconf_temp/conftest_7.cpp
In file included from /usr/include/c++/5/unordered_map:35:0,
from .sconf_temp/conftest_7.cpp:2:
/usr/include/c++/5/bits/c++0x_warning.h:32:2: error: #error This file
requires compiler and library support for the ISO C++ 2011 standard.
This support is currently experimental, and must be enabled with the
-std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support for the \
^
