Use C++ compiler when linking

Index: src/Makefile.am
--- src/Makefile.am.orig
+++ src/Makefile.am
@@ -9,6 +9,8 @@ sbin_PROGRAMS =
 bin_PROGRAMS =
 EXTRA_PROGRAMS =
 
+CCLD = $(CXX)
+
 AM_LDFLAGS = @GEOIP_LIBS@ @GEOIPV2_LIBS@
 if WITH_JANSSON
 AM_LDFLAGS += @JANSSON_LIBS@