IDL compiler: remove unused options

Simplification: removing Perl cruft.

--includes: unused: used by Perl b/c it searches for and reads arbitrary files
--verbose: unused
(specifying it prints the filename and then massive parser information;
if you need to debug the parser, you can set the flag at the call site)

Also makes some path handling a bit simpler.

BUG=341748
R=haraken

Review URL: https://codereview.chromium.org/150593004

git-svn-id: svn://svn.chromium.org/blink/trunk@166689 bbb929c8-8fbe-4397-9dbb-9b2b20218538