wscript: Fix waf syntax for svnversion.h

wscript

@@ -37,24 +37,24 @@ def display_feature(msg, build):
         display_msg(msg, "no", 'YELLOW')
 
 def create_svnversion_task(bld, header='svnversion.h', define=None):
-    import Constants, Build
-
     cmd = '../svnversion_regenerate.sh ${TGT}'
     if define:
         cmd += " " + define
 
-    cls = Task.simple_task_type('svnversion', cmd, color='BLUE', before='cc')
-    cls.runnable_status = lambda self: Constants.RUN_ME
-
     def post_run(self):
         sg = Utils.h_file(self.outputs[0].abspath(self.env))
         #print sg.encode('hex')
         Build.bld.node_sigs[self.env.variant()][self.outputs[0].id] = sg
-    cls.post_run = post_run
 
-    tsk = cls(bld.env.copy())
-    tsk.inputs = []
-    tsk.outputs = [bld.path.find_or_declare(header)]
+    bld(
+            rule = cmd,
+            name = 'svnversion',
+            runnable_status = Task.RUN_ME,
+            before = 'cc',
+            color = 'BLUE',
+            post_run = post_run,
+            target = [bld.path.find_or_declare(header)]
+    )
 
 def options(opt):
     # options provided by the modules