8296796: Provide clean, platform-agnostic interface to C-heap trimming

Reviewed-by: dholmes, rkennke

src/hotspot/os/linux/os_linux.inline.hpp

@@ -47,4 +47,13 @@ inline bool os::must_commit_stack_guard_pages() {
 inline void os::map_stack_shadow_pages(address sp) {
 }
 
+// Trim-native support
+inline bool os::can_trim_native_heap() {
+#ifdef __GLIBC__
+  return true;
+#else
+  return false; // musl
+#endif
+}
+
 #endif // OS_LINUX_OS_LINUX_INLINE_HPP