Cleanup implementation of formatter for std::vector from libstdc++.

[sivachandra]

Summary

Removed unused variables and methods.

examples/synthetic/gnu_libstdcpp.py

def has_children(self):
     return True
 
 class StdVectorSynthProvider:
 
   def __init__(self, valobj, dict):
     logger = lldb.formatters.Logger.Logger()
     self.count = None
     self.valobj = valobj
-    logger >> "Providing synthetic children for a map named " + str(valobj.GetName())
+    logger >> "Providing synthetic children for a vector named " + str(valobj.GetName())
 
   def num_children(self):
-    logger = lldb.formatters.Logger.Logger()
     if self.count == None:
       self.count = self.num_children_impl()
     return self.count
 
-  def is_valid_pointer(ptr,process):
-    logger = lldb.formatters.Logger.Logger()
-    error = lldb.SBError()
-    process.ReadMemory(ptr,1,error)
-    return False if error.Fail() else True
-
   def num_children_impl(self):
-    logger = lldb.formatters.Logger.Logger()
     try:
       start_val = self.start.GetValueAsUnsigned(0)
       finish_val = self.finish.GetValueAsUnsigned(0)
       end_val  = self.end.GetValueAsUnsigned(0)
       # Before a vector has been constructed, it will contain bad values
       # so we really need to be careful about the length we return since
       # unitialized data can cause us to return a huge number. We need
       # to also check for any of the start, finish or end of storage values
try:
         return 0
       else:
         num_children = num_children/self.data_size
       return num_children
     except:
       return 0;
 
   def get_child_index(self,name):
-    logger = lldb.formatters.Logger.Logger()
     try:
       return int(name.lstrip('[').rstrip(']'))
     except:
       return -1
 
   def get_child_at_index(self,index):
     logger = lldb.formatters.Logger.Logger()
     logger >> "Retrieving child " + str(index)
     if index < 0:
       return None;
     if index >= self.num_children():
       return None;
     try:
       offset = index * self.data_size
       return self.start.CreateChildAtOffset('['+str(index)+']',offset,self.data_type)
     except:
       return None
 
   def update(self):
-    logger = lldb.formatters.Logger.Logger()
     # preemptively setting this to None - we might end up changing our mind later
     self.count = None
     try:
       impl = self.valobj.GetChildMemberWithName('_M_impl')
       self.start = impl.GetChildMemberWithName('_M_start')
       self.finish = impl.GetChildMemberWithName('_M_finish')
       self.end = impl.GetChildMemberWithName('_M_end_of_storage')
       self.data_type = self.start.GetType().GetPointeeType()