[tools] Optimization the EXTERN_LIB variable use

tools/makefile.py

@@ -51,6 +51,14 @@ def TargetMakefile(env):
     if 'CXXFLAGS' in dir(rtconfig):
         make.write('CXXFLAGS :=%s' % (rtconfig.CXXFLAGS))
         make.write('\n')
+    if env.has_key('LIBS'):
+        make.write('EXTERN_LIB := ')
+        for tlib in env['LIBS']:
+            make.write('-l%s ' % (tlib))
+        if env.has_key('LIBPATH'):
+            for tlibpath in env['LIBPATH']:
+                make.write('-L%s ' % (tlibpath))
+        make.write('\n')
 
     make.write('\n')
 

tools/rtthread.mk

@@ -122,10 +122,10 @@ $(TARGET): $(OBJS)
 	@echo ar $(TARGET)
 	@$(CROSS_COMPILE)ar -rv $@ $(OBJS)
 else
-$(TARGET): $(OBJS) $(EXTERN_LIB)
+$(TARGET): $(OBJS)
 	@echo ------------------------------------------------
 	@echo link $(TARGET)
-	@$(CROSS_COMPILE)g++ -o $@ $(LFLAGS) $(OBJS) $(EXTERN_LIB) -lc -lm
+	@$(CROSS_COMPILE)g++ -o $@ $(LFLAGS) $(OBJS) $(EXTERN_LIB)
 	@echo ------------------------------------------------
 	@$(CROSS_COMPILE)objcopy -O binary $@ rtthread.bin
 	@$(CROSS_COMPILE)size $@