fixed b817c490 from https://gitee.com/arvinzzz/kernel_liteos_m/pulls/974

fix: 修复misc_config中defines未初始化的错误
Signed-off-by: Narvinzzz <zhaotianyu9@huawei.com>
Change-Id: I4eecfc1af2b0cdc39922a8ce299eb8ab6b7c6e8c

BUILD.gn

@@ -91,8 +91,9 @@ config("dialect_config") {
 }
 
 config("misc_config") {
+  defines = []
   if (!defined(LOSCFG_COMPILER_ICCARM)) {
-    defines = [ "__LITEOS__" ]
+    defines += [ "__LITEOS__" ]
     defines += [ "__LITEOS_M__" ]
   }
   if (!defined(LOSCFG_DEBUG_VERSION)) {