Merge pull request #2185 from yogpan01/master

Changing -O2 parameter to -Os

Author: 0xc0170

tools/toolchains/gcc.py

@@ -94,7 +94,7 @@ def __init__(self, target, options=None, notify=None, macros=None, silent=False,
             self.flags["common"].append("-g")
             self.flags["common"].append("-O0")
         else:
-            self.flags["common"].append("-O2")
+            self.flags["common"].append("-Os")
 
         main_cc = join(tool_path, "arm-none-eabi-gcc")
         main_cppc = join(tool_path, "arm-none-eabi-g++")