Format code around VCS conflict markers.

Now correctly formats:
  {
    int a;
    void f() {
      callme(some(parameter1,
  <<<<<<< text by the vcs
                  parameter2),
  ||||||| text by the vcs
                  parameter2),
             parameter3,
  ======= text by the vcs
                  parameter2, parameter3),
  >>>>>>> text by the vcs
             otherparameter);
    }
  }

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206157 91177308-0d34-0410-b5e6-96231b3b80d8