Summary:

Replace multiple occurrences of "ignoreUnrecognized" with a single global variable

Background:

Argument parsing in argument.cpp is very convoluted. Here's what it does in handling IgnoreUnrecognizedVMOptions:

[1] Scan all options specified provided by the following 4 sources, in this order:

     - JAVA_TOOL_OPTIONS env var
     - _JAVA_OPTIONS env var
     - options in the /java.base/jdk/internal/vm/options resource, if present
     - arguments passed to JNI_CreateJavaVM (from the java launcher, etc)

    (a) Find the last instance of -XX:[+-]IgnoreUnrecognizedVMOptions. Use that to decide the value of a boolean ignoreUnrecognized. If no such option is found, ignoreUnrecognized is false.

    (b) Find the last instance of -XX:Flags=flags_file, if present

[2] If flags_file is specified, parse all options from this file.

[3] Parse all options in the 4 sources listed in [1] (but strangely in a different order ....).

If an unrecognized option is found in [2] or [3], report an error ONLY if ignoreUnrecognized is false.

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Note: IgnoreUnrecognizedVMOptions is allowed to be used in flags_file, however, it has NO effect. Example:

$ echo "+IgnoreUnrecognizedVMOptions" > flags.txt
$ java -XX:Flags=flags.txt -XX:Foo=1 --version
Unrecognized VM option 'Foo=1'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

(This behavior is unspecified, and this RFE will NOT change this behavior)
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Proposal:

arguments.cpp stores ignoreUnrecognized in multiple variables, but they all have the exact same value. The value of these variables never change afterwards. Therefore, we can consolidate them into a single global.