8146115: Improve docker container detection and resource configuration usage

Reviewed-by: dholmes, kbarrett, phh

src/hotspot/os/bsd/os_bsd.cpp

@@ -3477,6 +3477,14 @@ void os::make_polling_page_readable(void) {
 }
 
 int os::active_processor_count() {
+  // User has overridden the number of active processors
+  if (ActiveProcessorCount > 0) {
+    log_trace(os)("active_processor_count: "
+                  "active processor count set by user : %d",
+                  ActiveProcessorCount);
+    return ActiveProcessorCount;
+  }
+
   return _processor_count;
 }