Remove the dependency on collections.deque().

This makes the OVM binary smaller.  There was no good reason for using
it in the first place!

osh/cmd_parse.py

@@ -10,7 +10,6 @@
cmd_parse.py - Parse high level shell commands.
"""

import collections
import sys

from core import braces
@@ -53,7 +52,7 @@ def Reset(self):
    self.c_kind = Kind.Undefined
    self.c_id = Id.Undefined_Tok

    self.pending_here_docs = collections.deque()
    self.pending_here_docs = []

  def Error(self):
    return self.error_stack
@@ -75,12 +74,7 @@ def GetCompletionState(self):
    return self.completion_stack

  def _MaybeReadHereDocs(self):
    while True:
      try:
        h = self.pending_here_docs.popleft()
      except IndexError:
        break

    for h in self.pending_here_docs:
      lines = []
      #log('HERE %r' % h.here_end)
      while True:
@@ -133,6 +127,7 @@ def _MaybeReadHereDocs(self):
        h.body = ast.CompoundWord(parts)
        h.was_filled = True

    self.pending_here_docs = []  # no .clear() until Python 3.3
    #print('')
    #print('--> FILLED', here_docs)
    #print('')