python-scan: avoid possible deadlock passing list of modules to the api scanner process

bindings/python/ns3modulescan.py

@@ -253,7 +253,7 @@ class MyPygenClassifier(PygenClassifier):
 
 def ns3_module_scan(top_builddir, pygen_file_name, everything_h, cflags):
 
-    ns3_modules = eval(sys.stdin.read())
+    ns3_modules = eval(sys.stdin.readline())
 
     ## do a topological sort on the modules graph
     from topsort import topsort

bindings/python/wscript

@@ -437,7 +437,7 @@ class python_scan_task(Task.TaskBase):
             self.cflags,
             ]
         scan = subprocess.Popen(argv, stdin=subprocess.PIPE)
-        scan.stdin.write(repr(get_modules_and_headers(self.bld)))
+        print >> scan.stdin, repr(get_modules_and_headers(self.bld))
         scan.stdin.close()
         retval = scan.wait()
         return retval