8056071: compiler/whitebox/IsMethodCompilableTest.java fails with 'method() is not compilable after 3 iterations'

Always use MDO if valid and always compile trivial methods with C1 if available.

Reviewed-by: kvn, iveresov

hotspot/src/share/vm/oops/method.hpp

@@ -595,6 +595,9 @@ class Method : public Metadata {
   // returns true if the method is an accessor function (setter/getter).
   bool is_accessor() const;
 
+  // returns true if the method does nothing but return a constant of primitive type
+  bool is_constant_getter() const;
+
   // returns true if the method is an initializer (<init> or <clinit>).
   bool is_initializer() const;