重新整理libc重复共用文件，创建common_for_all 和 common_for_keiliar

components/libc/compilers/common/SConscript

@@ -1,27 +0,0 @@
-from building import *
-
-Import('rtconfig')
-
-src   = []
-cwd   = GetCurrentDir()
-group = []
-CPPPATH = [cwd]
-
-if GetDepend('RT_USING_LIBC'):
-    src += Glob('*.c')
-else:
-    if GetDepend('RT_LIBC_USING_TIME'):
-        src += ['time.c']
-
-if GetDepend('RT_USING_POSIX') == False:
-    SrcRemove(src, ['unistd.c'])
-
-if rtconfig.CROSS_TOOL == 'keil':
-    CPPDEFINES = ['__CLK_TCK=RT_TICK_PER_SECOND']
-else:
-    CPPDEFINES = []
-
-if GetDepend('RT_USING_LIBC') or GetDepend('RT_LIBC_USING_TIME'):
-    group = DefineGroup('libc', src, depend = [''], CPPPATH = CPPPATH, CPPDEFINES = CPPDEFINES)
-
-Return('group')