Fix SF bug [ #450245 ] Error in parsing future stmts

Add test case to cover multiple future statements on separate lines of
a module.

Lib/test/output/test_future

@@ -1,6 +1,7 @@
 test_future
 6
 6
+2
 SyntaxError badsyntax_future3 3
 SyntaxError badsyntax_future4 3
 SyntaxError badsyntax_future5 4

Lib/test/regrtest.py

@@ -214,6 +214,7 @@ NOTTESTS = [
     'test_b2',
     'test_future1',
     'test_future2',
+    'test_future3',
     ]
 
 def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):

Lib/test/test_future.py

@@ -17,6 +17,9 @@ import test_future1
 unload('test_future2')
 import test_future2
 
+unload('test_future3')
+import test_future3
+
 # The remaining tests should fail
 try:
     import badsyntax_future3