don't make a empty directory "DeviceDrivers" in IAR project while...

don't make a empty directory "DeviceDrivers" in IAR project while RT_USING_MTD_NOR or RT_USING_MTD_NAND was not defined in rtconfig.h

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2169 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/drivers/mtd/SConscript

@@ -9,12 +9,14 @@ mtd_nor = ['mtd_nor.c']
 
 mtd_nand = ['mtd_nand.c']
 
+CPPPATH = [cwd + '/../include']
+group = []
+
 if GetDepend(['RT_USING_MTD_NOR']):
     src = src + mtd_nor
+    group = DefineGroup('DeviceDrivers', src, depend = ['RT_USING_MTD_NOR'], CPPPATH = CPPPATH)
 if GetDepend(['RT_USING_MTD_NAND']):
     src = src + mtd_nand
-
-CPPPATH = [cwd + '/../include']
-group = DefineGroup('DeviceDrivers', src, depend = [''], CPPPATH = CPPPATH)
+    group = DefineGroup('DeviceDrivers', src, depend = ['RT_USING_MTD_NAND'], CPPPATH = CPPPATH)
 
 Return('group')