添加rtthread相关代码

riscv/rtthread/components/drivers/clk/SConscript

@@ -0,0 +1,26 @@
+from building import *
+
+group = []
+objs = []
+
+if not GetDepend(['RT_USING_CLK']):
+    Return('group')
+
+cwd = GetCurrentDir()
+list = os.listdir(cwd)
+CPPPATH = [cwd + '/../include']
+
+src = ['clk.c']
+
+if GetDepend(['RT_USING_OFW']):
+    src += ['clk-fixed-rate.c']
+
+group = DefineGroup('DeviceDrivers', src, depend = [''], CPPPATH = CPPPATH)
+
+for d in list:
+    path = os.path.join(cwd, d)
+    if os.path.isfile(os.path.join(path, 'SConscript')):
+        objs = objs + SConscript(os.path.join(d, 'SConscript'))
+objs = objs + group
+
+Return('objs')