Remove terminally deprecated constructors in java.base

Summary

Remove terminally deprecated constructors in java.lang.reflect.Modifier and java.lang.invoke.ConstantBootstraps.

Problem

The constructors that were previously marked as deprecated are in need of removal.

Solution

Remove the constructors in question. Note as raised in the core-libs review thread, at least one non-public constructor needs to be added to preserve the effect of removing these public constructors. The implementation will use no-arg private constructors.

Specification

--- a/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java  Sat Dec 07 09:40:28 2019 +0800
+++ b/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java  Sun Dec 08 10:49:48 2019 -0800
@@ -40,12 +40,6 @@
  * @since 11
  */
 public final class ConstantBootstraps {
-    /**
-     * Do not call.
-     */
-    @Deprecated(forRemoval=true, since="14")
-    public ConstantBootstraps() {}
-
     // implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
     /*non-public*/
     static Object makeConstant(MethodHandle bootstrapMethod,
diff -r 31882abe1494 src/java.base/share/classes/java/lang/reflect/Modifier.java
--- a/src/java.base/share/classes/java/lang/reflect/Modifier.java   Sat Dec 07 09:40:28 2019 +0800
+++ b/src/java.base/share/classes/java/lang/reflect/Modifier.java   Sun Dec 08 10:49:48 2019 -0800
@@ -44,13 +44,6 @@
  */
 public class Modifier {
     /**
-     * Do not call.
-     */
-    @Deprecated(forRemoval=true, since="14")
-    public Modifier() {}
-
-
-    /**
      * Return {@code true} if the integer argument includes the
      * {@code public} modifier, {@code false} otherwise.
      *