message: [indexer] Change macro's IndexVar::def::detail_name to its approximate definition
  For `#define foo 3`,
  Before this commit, `detail_name` was `foo` (displayed for textDocument/hover reqeusts).
  It is now shown as `#define foo 3`
diff: @@ -923,13 +923,14 @@ ClangCursor::VisitResult VisitMacroDefinitionAndExpansions(ClangCursor cursor,
  UniqueAdd(var_def->uses, decl_loc_spelling);
  if (cursor.get_kind() == CXCursor_MacroDefinition) {
  + CXSourceRange cx_extent = clang_getCursorExtent(cursor.cx_cursor);
  var_def->def.short_name = cursor.get_display_name();
  - var_def->def.detailed_name = var_def->def.short_name;
  var_def->def.is_local = false;
  var_def->def.is_macro = true;
  var_def->def.definition_spelling = decl_loc_spelling;
  - var_def->def.definition_extent = ResolveExtent(cursor.cx_cursor);
  - ;
  + var_def->def.definition_extent = Resolve(cx_extent, nullptr);
  + var_def->def.detailed_name =
  + "#define " + GetDocumentContentInRange(param->tu->cx_tu, cx_extent);
  }
  break;
  