<AWT Dev> RfR JDK-8055160

[Pete Brunet]

The following patch to accessibility related code is for the modularity
effort.

http://cr.openjdk.java.net/~ptbrunet/JDK-8055160/webrev.00/

The Java Access Bridge (which provides access to Java for example by
screen readers used by those who are blind) is currently loaded by
Toolkit via reflection as a JDK specific feature.  The prior means of
loading the JAB relies on the Java extension mechanism and the JAB class
file being located in lib/ext.  The Java extension mechanism no longer
exits in Java 9.  The new code uses a service provider interface in
preparation for loading the Java Access Bridge and other service
provider implementations as modules.

The following is the change to java.awt.Toolkit.

jdk/src/java.desktop/share/classes/java/awt/Toolkit.java

The following defines the new accessibility SPI (Service Provider
Interface).

jdk/src/java.desktop/share/classes/javax/accessibility/AccessibilitySPI.java

The following are tests for the new service provider.

jdk/test/javax/accessibility/AccessibilitySPI/FooProvider.java
jdk/test/javax/accessibility/AccessibilitySPI/Load.java
jdk/test/javax/accessibility/AccessibilitySPI/basic.sh