RFR: JDK10: JDK-8180334: Unable to build jaotc launcher on windows

[Kumar Srinivasan]

Hello,

Please review the changes to fix  JDK-8180334,  essentially -DJAVA_ARGS 
exceeds
a Visual Studio C++ compiler limit, and this fix provides a way to specify
very long  string literals, by the build system.

This also includes some minor and subtle simplifications and cleanups wrt.
the JAVA_ARGS and its handling.

Thanks

Webrev: http://cr.openjdk.java.net/~ksrini/8180334/webrev.00
JBS: https://bugs.openjdk.java.net/browse/JDK-8180334