Make TrimNativeHeapInterval a product switch

Summary

Make TrimNativeHeapInterval a product switch

Problem

JDK-8293114 introduced automatic C-heap trimming, for now supported only by the glibc. It is controlled by the command line switch TrimNativeHeapInterval. The feature has proven to be very valuable to customers, and all issues have been ironed out. Therefore, I propose to make this switch a non-experimental product switch.

Solution

The solution is to remove the EXPERIMENTAL moniker from this switch.

In addition to that, the java man page will be changed to mention this option as well as its limitation to Linux glibc-based systems.

In addition to that, a release note will be written.

Specification

--- a/src/hotspot/share/runtime/globals.hpp
+++ b/src/hotspot/share/runtime/globals.hpp
@@ -1996,7 +1996,7 @@ const int ObjectAlignmentInBytes = 8;
           "2: monitors & new lightweight locking (LM_LIGHTWEIGHT)")         \
           range(0, 2)                                                       \
                                                                             \
-  product(uint, TrimNativeHeapInterval, 0, EXPERIMENTAL,                    \
+  product(uint, TrimNativeHeapInterval, 0,                                  \
           "Interval, in ms, at which the JVM will trim the native heap if " \
           "the platform supports that. Lower values will reclaim memory "   \
           "more eagerly at the cost of higher overhead. A value of 0 "      \