Compile LuaJIT with LUAJIT_USE_PERFTOOLS and LUAJIT_USE_GDBJIT.

These are valuable debugging tools and they have no immediately
obvious performance impact.

Particularly useful is LUAJIT_USE_PERFTOOLS so that Linux 'perf top'
will show individual traces.

Makefile

@@ -5,11 +5,17 @@ COBJ   = $(CSRC:.c=.o)
 
 LUAJIT_O := deps/luajit/src/libluajit.a
 
+LUAJIT_CFLAGS := -DLUAJIT_USE_PERFTOOLS -DLUAJIT_USE_GDBJIT
+
 all: $(LUAJIT_O)
 	cd src && $(MAKE)
 
 $(LUAJIT_O): deps/luajit/Makefile
-	(echo 'Building LuaJIT\n'; cd deps/luajit && $(MAKE) PREFIX=`pwd`/usr/local && $(MAKE) DESTDIR=`pwd` install)
+	echo 'Building LuaJIT\n'
+	(cd deps/luajit && \
+	 $(MAKE) PREFIX=`pwd`/usr/local \
+	         CFLAGS="$(LUAJIT_CFLAGS)" && \
+	 $(MAKE) DESTDIR=`pwd` install)
 	(cd deps/luajit/usr/local/bin; ln -fs luajit-2.1.0-alpha luajit)
 
 clean: