RFR v4 - 8027634: Support @argfiles for java command-line tool

[Henry Jen]

Hi,

Another update for argument file support, this version we added a couple measures to ensure compatibility,

1) Compile time directive ENABLE_ARG_FILES is needed to enable the feature, only java is enabled with this webrev.
2) Escape @argument if so desired: Additional prefixes of @ to a @ prefixed option will  act as an escape, ie. the first @ will be removed and the rest of the arguments presented to the launcher literally.
 
For example:
 
java @ foo  gets arguments of @ foo
java @filename, filename expanded
java @@filename will have the leading @ removed and reduced to literal @filename
similarly,
java @@@filenamewill have the leading @ removed and reduced to literal @@filename
 
 3) The option '-Xdisable- at files' can be used on the command line anywhere to prevent further @filename expansion.
 4) Limit the file size must not exceed MAXINT (2, 147, 483, 647) bytes.

Webrev at http://cr.openjdk.java.net/~henryjen/jdk9/8027634/v4/webrev/

Cheers,
Henry