Some PLAB related flags' validation can happen after heap creation. Introduced additional stage of validation check.
Reviewed-by: coleenp, dholmes, kbarrett, gziemski, ecaspole, ddmitriev
Validate the arguments to all JVM command-line flags so as to avoid crashes, and ensure that appropriate error messages are displayed when they are invalid.
Reviewed-by: ddmitriev, dholmes, kbarrett, drwhite, brutisso, coleenp
