Deprecate UnlinkSymbolsALot debugging option

Summary

Deprecate UnlinkSymbolsALot debugging option and make obsolete in JDK 12.

Problem

This option was added during development erroneously as a product option.

Support for the code that this option calls will be removed when we check in the concurrent SymbolTable in JDK 12.

Solution

The option will be made obsolete and a warning message that it is obsolete will be printed.

% java -XX:+UnlinkSymbolsALot -version Java HotSpot(TM) 64-Bit Server VM warning: Option UnlinkSymbolsALot was deprecated in version 11.0 and will likely be removed in a future release. java version "11-internal" 2018-09-25 Java(TM) SE Runtime Environment 18.9 (fastdebug build 11-internal+0-2018-06-20-1156371.cphillim.11unlink-symbols) Java HotSpot(TM) 64-Bit Server VM 18.9 (fastdebug build 11-internal+0-2018-06-20-1156371.cphillim.11unlink-symbols, mixed mode)

Specification

Webrev with changes to make UnlinkSymbolsALot obsolete.

http://cr.openjdk.java.net/~coleenp/8205175.01/webrev/index.html

Patch:

--- old/src/hotspot/share/runtime/arguments.cpp 2018-06-20 09:21:18.609402155 -0400
+++ new/src/hotspot/share/runtime/arguments.cpp 2018-06-20 09:21:18.051350782 -0400
@@ -540,6 +540,7 @@
   { "PrintSafepointStatisticsCount",JDK_Version::jdk(11), JDK_Version::jdk(12), JDK_Version::jdk(13) },
   { "AggressiveOpts",               JDK_Version::jdk(11), JDK_Version::jdk(12), JDK_Version::jdk(13) },
   { "AllowNonVirtualCalls",         JDK_Version::jdk(11), JDK_Version::jdk(12), JDK_Version::jdk(13) },
+  { "UnlinkSymbolsALot",            JDK_Version::jdk(11), JDK_Version::jdk(12), JDK_Version::jdk(13) },

   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
   { "DefaultMaxRAMFraction",        JDK_Version::jdk(8),  JDK_Version::undefined(), JDK_Version::undefined() },