Recognize the main module header as well as different #include categories.
This should now mimic the behavior of llvm/utils/sort_includes.py as
well as clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp very
closely.
llvm-svn: 248782
To implement this nicely, add a function that merges two sets of
replacements that are meant to be done in sequence. This functionality
will also be useful for other applications, e.g. formatting the result
of clang-tidy fixes.
llvm-svn: 248367