build: do not install syslog_override for the RPM packaging

tests/Makefile.am

@@ -150,7 +150,7 @@ log_test_LDADD = $(top_builddir)/lib/libqb.la @CHECK_LIBS@
 if HAVE_SYSLOG_TESTS
 log_test_LDADD += _syslog_override.la
 
-lib_LTLIBRARIES = _syslog_override.la
+check_LTLIBRARIES = _syslog_override.la
 _syslog_override_la_SOURCES = _syslog_override.c _syslog_override.h
 _syslog_override_la_LDFLAGS = -module
 endif