Suppress errors from config-test-flags macro.

Author: solemnwarning

Makefile

@@ -30,8 +30,8 @@ pkg-select-ab = $\
 config-test-flag = $\
 	$(if $(wildcard $(1).aok)$(wildcard $(1).bok),, \
 		$(info Checking if we need $(2)...) \
-		$(shell $(CXX) $(CXXFLAGS) -o $(1).aok $(1) $(LDFLAGS) $(LDLIBS)      > /dev/null) \
-		$(shell $(CXX) $(CXXFLAGS) -o $(1).bok $(1) $(LDFLAGS) $(LDLIBS) $(2) > /dev/null) \
+		$(shell $(CXX) $(CXXFLAGS) -o $(1).aok $(1) $(LDFLAGS) $(LDLIBS)      > /dev/null 2>&1) \
+		$(shell $(CXX) $(CXXFLAGS) -o $(1).bok $(1) $(LDFLAGS) $(LDLIBS) $(2) > /dev/null 2>&1) \
 		$(if $(wildcard $(1).aok),$(info No),$(if $(wildcard $(1).bok),$(info Yes),)) \
 	) \
 	$(if $(wildcard $(1).aok),,$(if $(wildcard $(1).bok),$(2),))