Attempt to fix the parser caching in the IDL compiler.

PLY has a feature where it'll load a generated lexer
table by importing it as a python module. It turns out
that we were being inconsistent in how we were generating
these modules and that could lead to incomplete builds depending
on when the various IDL compilation targets ran.

This CL attempts to be more consistent about the generation
of the cached files to eliminate that problem, by requiring
the scripts to consistently pass in the location of the cached
files. We can't really fix this without doing more serious
surgery on PLY (or working around it) to be more deterministic
in how the cached file is imported.

R=dcheng@chromium.org, haraken@chromium.org
BUG=1022647

Change-Id: I141059341634633f0df33848638eecc432aa764c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903938
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713872}