clang-reorder-fields mishandles macros

[tavianator]

When macros are used in an initializer, clang-reorder-fields edits the macros themselves instead of reordering their uses. Example:

$ cat foo.c
struct foo {
  int bar;
  int baz;
};

#define BAR 0
#define BAZ 1

struct foo global = {
  BAR,
  BAZ,
};
$ clang-reorder-fields --record-name=foo --fields-order=baz,bar foo.c --
struct foo {
  int baz;
  int bar;
};

#define BAR BAZ
#define BAZ BAR

struct foo global = {
  BAR,
  BAZ,
};