创建，添加sdram

rt-thread/libcpu/arm/common/SConscript

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+# RT-Thread building script for component
+
+from building import *
+
+Import('rtconfig')
+
+cwd     = GetCurrentDir()
+src     = Glob('*.c') + Glob('*.cpp')
+CPPPATH = [cwd]
+
+if rtconfig.PLATFORM in ['armcc', 'armclang']:
+    src += Glob('*_rvds.S')
+
+if rtconfig.PLATFORM in ['gcc']:
+    src += Glob('*_init.S')
+    src += Glob('*_gcc.S')
+
+if rtconfig.PLATFORM in ['iccarm']:
+    src += Glob('*_iar.S')
+
+if not GetDepend('RT_USING_HW_ATOMIC'):
+    SrcRemove(src, 'atomic_arm.c')
+
+group = DefineGroup('libcpu', src, depend = [''], CPPPATH = CPPPATH)
+
+Return('group')