Rename bootstrap_compiler.py to build_tool.py.

TEST=None
BUG=None

Change-Id: I33d914575c17f4c2b6535ecdbdc474759e9f8f56
Reviewed-on: https://chrome-internal-review.googlesource.com/160841
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Han Shen <shenhan@google.com>
Tested-by: Han Shen <shenhan@google.com>
diff --git a/bootstrap_compiler.py b/build_tool.py
similarity index 100%
rename from bootstrap_compiler.py
rename to build_tool.py