8010722: assert: failed: heap size is too big for compressed oops

Use conservative assumptions of required alignment for the various garbage collector components into account when determining the maximum heap size that supports compressed oops. Using this conservative value avoids several circular dependencies in the calculation.

Reviewed-by: stefank, dholmes

hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -2191,6 +2191,10 @@ jint G1CollectedHeap::initialize() {
   return JNI_OK;
 }
 
+size_t G1CollectedHeap::conservative_max_heap_alignment() {
+  return HeapRegion::max_region_size();
+}
+
 void G1CollectedHeap::ref_processing_init() {
   // Reference processing in G1 currently works as follows:
   //