[iar] 修正IAR编译链名称

tools/building.py

@@ -173,7 +173,7 @@ def PrepareBuilding(env, root_directory, has_libcpu=False, remove_components = [
     tgt_dict = {'mdk':('keil', 'armcc'),
                 'mdk4':('keil', 'armcc'),
                 'mdk5':('keil', 'armcc'),
-                'iar':('iar', 'iar'),
+                'iar':('iar', 'iccarm'),
                 'vs':('msvc', 'cl'),
                 'vs2012':('msvc', 'cl'),
                 'vsc' : ('gcc', 'gcc'),