fix FTBFS, c++ linking needs -lstdc++ explicitly
https://bugzilla.redhat.com/show_bug.cgi?id=631288

--- apcupsd-3.14.13/src/Makefile~	2014-11-04 21:17:43.000000000 +0200
+++ apcupsd-3.14.13/src/Makefile	2015-09-16 16:42:11.150220917 +0300
@@ -30,10 +30,10 @@
 all-targets: apcupsd$(EXE) apcaccess$(EXE) apctest$(EXE) smtp$(EXE) 
 
 apcupsd$(EXE): $(common_obj) $(apcupsd_obj) $(APCDRVLIBS) $(APCLIBS)
-	$(LINK) $(DRVLIBS) $(BG)
+	$(LINK) -lstdc++ $(DRVLIBS) $(BG)
 
 apctest$(EXE): $(common_obj) $(apctest_obj) $(APCDRVLIBS) $(APCLIBS)
-	$(LINK) $(DRVLIBS)
+	$(LINK) -lstdc++ $(DRVLIBS)
 
 apcaccess$(EXE): $(apcaccess_obj) $(APCLIBS)
 	$(LINK)