Improve efficiency of PreloadSupplier and RegionDataBuilder.

before: RegionDataBuilderTest.BuildCnRegionTree (8485 ms)
after: RegionDataBuilderTest.BuildCnRegionTree (5765 ms)
 => 32% improvement.

(Built using 'g++ -g -pg -O0')

R=roubert@google.com

Review URL: https://codereview.appspot.com/111390043
7 files changed
tree: c23060e383758d966f253721a99efebe059dbe07
  1. cpp/
  2. externals/
  3. java/
  4. testdata/
  5. .gitmodules
  6. codereview.settings