[cpp] attach CXXFLAGS to reduce the resource consumptions

components/libc/cplusplus/SConscript

@@ -1,12 +1,16 @@
 from building import *
 import os
-Import('rtconfig')
+import rtconfig
 
 cwd     = GetCurrentDir()
 src     = ['cxx_crt_init.c', 'cxx_crt.cpp']
 CPPPATH = [cwd]
+CXXFLAGS = ''
 
-group = DefineGroup('CPP', src, depend=['RT_USING_CPLUSPLUS'], CPPPATH=CPPPATH)
+if rtconfig.PLATFORM in ['gcc', 'armclang', 'llvm-arm']: # GCC or Keil AC6 or Clang/LLVM
+    CXXFLAGS += ' -fno-exceptions -fno-rtti -ffunction-sections -fdata-sections -Wl,--gc-sections' # reduce the resource consumptions
+
+group = DefineGroup('CPP', src, depend=['RT_USING_CPLUSPLUS'], CPPPATH=CPPPATH, CXXFLAGS=CXXFLAGS)
 
 list = os.listdir(cwd)
 for d in list: