update arg names to mx_fastr.rcmplib

mx.fastr/mx_fastr.py

@@ -326,15 +326,15 @@ def rbcheck(args):
 
 def rcmplib(args):
     '''compare FastR library R sources against GnuR'''
-    parser = ArgumentParser(prog='mx cmplibr')
+    parser = ArgumentParser(prog='mx rcmplib')
     parser.add_argument('--gnurhome', action='store', help='path to GnuR sources', required=True)
-    parser.add_argument('--lib', action='store', help='library to check', default="base")
+    parser.add_argument('--package', action='store', help='package to check', default="base")
     args = parser.parse_args(args)
     cmpArgs = []
     cmpArgs.append("--gnurhome")
     cmpArgs.append(args.gnurhome)
-    cmpArgs.append("--lib")
-    cmpArgs.append(args.lib)
+    cmpArgs.append("--package")
+    cmpArgs.append(args.package)
     cp = mx.classpath([pcp.name for pcp in mx.projects_opt_limit_to_suites()])
     mx.run_java(['-cp', cp, 'com.oracle.truffle.r.test.tools.cmpr.CompareLibR'] + cmpArgs)