Summary:
This is a simple edit to have two #include file paths be consistent within range_del_aggregator.{h,cc} with everywhere else.

The impact of this inconsistency is that it actual breaks a Bazel based build on the Windows platform. The same pragma once failure occurs with both Windows Visual C++ 2019 and clang for Windows 9.0. Bazel's "sandboxing" of the builds causes both compilers to not properly recognize "rocksdb/types.h" and "include/rocksdb/types.h" to be the same file (also comparator.h). My guess is that the backslash versus forward slash mixing within path names is the underlying issue.

But, everything builds fine once the include paths in these two source files are consistent with the rest of the repository.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6321

Differential Revision: D19506585

Pulled By: ltamasi

fbshipit-source-id: 294c346607edc433ab99eaabc9c880ee7426817a