fix library linking error

Makefile

@@ -4,16 +4,16 @@ version=0.1
 name=lua-resty-qrencode
 LUA_VERSION =   5.1
 
+CC=gcc
 # See http://lua-users.org/wiki/BuildingModules for platform specific
 # details.
 
 ## Linux/BSD
 PREFIX ?=          /usr/local/openresty
-#LDFLAGS +=         -shared
-
+LDFLAGS +=         -shared -lpng -lqrencode
 ## OSX (Macports)
 #PREFIX ?=          /opt/local
-LDFLAGS +=         -bundle -undefined dynamic_lookup
+#LDFLAGS +=         -bundle -undefined dynamic_lookup
 
 ## find your luajit path
 LUA_INCLUDE_DIR ?= $(PREFIX)/luajit/include/luajit-2.1
@@ -22,9 +22,9 @@ LUA_LIB_DIR ?=     $(PREFIX)/lualib
 # Some versions of Solaris are missing isinf(). Add -DMISSING_ISINF to
 # CFLAGS to work around this bug.
 
-#CFLAGS ?=          -g -Wall -pedantic -fno-inline
-CFLAGS ?=          -g -O3 -Wall -pedantic
-override CFLAGS += -fpic -I$(LUA_INCLUDE_DIR) -lpng -lqrencode
+CFLAGS ?=          -g -Wall -pedantic -fno-inline
+#CFLAGS ?=          -g -O3 -Wall -pedantic
+override CFLAGS += -fpic -I$(LUA_INCLUDE_DIR)
 
 INSTALL ?= install
 
@@ -33,7 +33,7 @@ INSTALL ?= install
 all: qrencode.so
 
 qrencode.so: qrencode.c
-	$(CC) $(LDFLAGS) $(CFLAGS) -o $@ $^
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 
 install:
 	$(INSTALL) -d $(LUA_LIB_DIR)