Make runguard a C++ program.

Next step of https://docs.google.com/document/d/1WZRwdvJUamsczYC7CpP3ZIBU8xG6wNqYqrNJf7osxYs/edit

Author: meisterT

judge/Makefile

@@ -13,14 +13,12 @@ judgehost: $(TARGETS) $(SUBST_FILES)
 $(SUBST_FILES): %: %.in $(TOPDIR)/paths.mk
 	$(substconfigvars)
 
-runguard: LDFLAGS := $(filter-out -pie,$(LDFLAGS))
-
-runguard: -lm $(LIBCGROUP)
-runguard$(OBJEXT): $(TOPDIR)/etc/runguard-config.h
-
 evict: evict.c $(LIBHEADERS) $(LIBSOURCES)
 	$(CC) $(CFLAGS) -o $@ $< $(LIBSOURCES)
 
+runguard: runguard.cc $(LIBHEADERS) $(LIBSOURCES) $(TOPDIR)/etc/runguard-config.h
+	$(CXX) $(CXXFLAGS) -o $@ $< $(LIBSOURCES) $(LIBCGROUP)
+
 runpipe: runpipe.cc $(LIBHEADERS) $(LIBSOURCES)
 	$(CXX) $(CXXFLAGS) -static -o $@ $< $(LIBSOURCES)