dumpapi: dump @hide in a single line

@hide in comments is dumped in a legacy-style single line to pass
legacy diff-based --checkapi.

Bug: 179449077
Test: aidl_unittests
Change-Id: I3356c7dc1d78330fe3b0ab4bce2db66bebc58ace
diff --git a/aidl_dumpapi.cpp b/aidl_dumpapi.cpp
index 06eb089..6c7ef78 100644
--- a/aidl_dumpapi.cpp
+++ b/aidl_dumpapi.cpp
@@ -58,7 +58,11 @@
 void DumpVisitor::DumpComments(const AidlCommentable& c) {
   const auto hidden = c.IsHidden();
   const auto deprecated = FindDeprecated(c.GetComments());
-  if (hidden || deprecated) {
+  if (hidden && !deprecated) {
+    // to pass --checkapi between the current and the tot in the mainline-prod branch
+    // emit @hide in a legacy dump style
+    out << "/* @hide */\n";
+  } else if (hidden || deprecated) {
     out << "/**\n";
     if (hidden) {
       out << " * @hide\n";