GROOVY-8588 use lowercase -v for --version in groovyc to be consisten…

…t with other Groovy command line tools (closes #710)

src/main/java/org/codehaus/groovy/tools/FileSystemCompiler.java

@@ -166,7 +166,6 @@ public static void commandLineCompile(String[] args, boolean lookupUnnamedFiles)
 
     public static CommandLine configureParser(CompilationOptions options) {
         CommandLine parser = new CommandLine(options);
-        parser.getCommandSpec().mixinStandardHelpOptions(true); // programmatically so these options appear last in usage help
         parser.getCommandSpec().parser()
                 .unmatchedArgumentsAllowed(true)
                 .unmatchedOptionsArePositionalParams(true)
@@ -350,6 +349,12 @@ public static class CompilationOptions {
         @Option(names = {"--configscript"}, paramLabel = "<script>", description = "A script for tweaking the configuration options")
         private String configScript;
 
+        @Option(names = {"-h", "--help"}, usageHelp = true, description = "Show this help message and exit")
+        private boolean helpRequested;
+
+        @Option(names = {"-v", "--version"}, versionHelp = true, description = "Print version information and exit")
+        private boolean versionRequested;
+
         @Parameters(description = "The groovy source files to compile, or @-files containing a list of source files to compile",
                     paramLabel = "<source-files>")
         private List<String> files;