[clang-format] Do not emit replacements while regrouping if Cpp includes are OK
Summary:
Currently clang-format would always emit a replacement for multi-block #include
sections if `IBS_Regroup`, even if the sections are correct:
```
% cat ~/test.h
#include <a.h>
#include "b.h"
% bin/clang-format --output-replacements-xml -style=google ~/test.h
<?xml version='1.0'?>
<replacements xml:space='preserve' incomplete_format='false'>
<replacement offset='0' length='30'>#include <a.h> #include "b.h"</replacement>
</replacements>
%
```
This change makes clang-format not emit replacements in this case.
The logic is similar to the one implemented for Java in r354452.
Reviewers: ioeric
Reviewed By: ioeric
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D60199
llvm-svn: 357599