Don't use C++ for gnutls/mingw32

extras/contrib/src/Makefile

@@ -1880,7 +1880,7 @@ endif
 
 .gnutls: gnutls .opencdk .gcrypt .gpg-error 
 ifdef HAVE_WIN32
-	(cd $<; autoconf && $(HOSTCC) ./configure $(HOSTCONF) --prefix=$(PREFIX) CFLAGS="$(CFLAGS)" --target=i586-mingw32msvc && cd gl && make && cd ../lgl && make &&  cd ../lib &&make && make install && cd ../includes && make install)
+	(cd $<; autoconf && $(HOSTCC) ./configure $(HOSTCONF) --prefix=$(PREFIX) CFLAGS="$(CFLAGS)" --target=i586-mingw32msvc --disable-cxx && cd gl && make && cd ../lgl && make &&  cd ../lib &&make && make install && cd ../includes && make install)
 else
 	(cd $<; $(HOSTCC) ./configure $(HOSTCONF) --prefix=$(PREFIX) CFLAGS="$(CFLAGS)" --disable-cxx --with-libopencdk-prefix=$(PREFIX) --disable-guile && make && make install)
 endif