RFR: 8159855

[Jonathan Gibbons]

Core-libs folk,

Please review the following change to add a new service provider class
     java.util.spi.ToolProvider

which can be used provide simple "command-line" access to select JDK
tools, without starting a new JVM.

The following tools are updated to provide access through the new SPI:
     javac, javadoc, javap, jdeps

It is expected that additional tools will also be updated to provide access,
but that will be done separately.

Compiler-dev folk may wish to review the changes to the langtools 
repository.

JBS: https://bugs.openjdk.java.net/browse/JDK-8159855
Webrev: http://cr.openjdk.java.net/~jjg/8159855/webrev.03/
API: 
http://cr.openjdk.java.net/~jjg/8159855/api.02/java/util/spi/ToolProvider.html

-- Jon