Buildsystem wants CXX to be defined as $(CXX).
Otherwise it fallbacks to default value, which does not contain
"-std=c++11" statement.
Other changes (like CC=$(CC) and CFLAGS=$(CFLAGS) instead of CXX ones)
is not directly fix the issue, but fix cases, where CFLAGS (and CC)
differs from CXX* ones, so it could lead to similar errors in the future.
PDOC_START = bindings/python/sigrok/core/doc_start.i
PDOC_END = bindings/python/sigrok/core/doc_end.i
-setup_vars = VERSION='$(PACKAGE_VERSION)' CC='$(CXX)' CFLAGS='$(CXXFLAGS) $(SR_WXXFLAGS) $(PYSIGROK_CFLAGS)' CXXFLAGS='$(CXXFLAGS) $(SR_WXXFLAGS) $(PYSIGROK_CFLAGS)' LDADD='$(PYSIGROK_LIBS)'
+setup_vars = VERSION='$(PACKAGE_VERSION)' CC='$(CC)' CXX='$(CXX)' CFLAGS='$(CFLAGS) $(SR_WXXFLAGS) $(PYSIGROK_CFLAGS)' CXXFLAGS='$(CXXFLAGS) $(SR_WXXFLAGS) $(PYSIGROK_CFLAGS)' LDADD='$(PYSIGROK_LIBS)'
setup_quiet = --quiet
setup_py = $(PYTHON) $(srcdir)/$(PDIR)/setup.py $(setup_vars) $(setup_quiet)