Have JspC initialize its ClassLoader before the ServletContext.
This avoids the need to re-initialize the ClassLoader for every JSP being pre-compiled.
It also allows the ServletContext to be used before starting a compilation run, e.g. to scan for TLDs

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1513025 13f79535-47bb-0310-9956-ffa450edef68