Use the file name directly and remove the now unused getFile() method

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1634719 13f79535-47bb-0310-9956-ffa450edef68
registerSourceFile() is only called from the constructor.
At this point sourceFiles is always empty so registerSourceFile() will
always return zero.
That makes the code that follows registerSourceFile() always a NO-OP
which in turn removes the need for calling registerSourceFile() in the
first place.
Remove soucrceFiles as unused.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1634720 13f79535-47bb-0310-9956-ffa450edef68