report error on global enum

rather than segfault when running
bookmaker cross check, report
a parsable error.

In a separate CL, I'll add support
for global enums.

R=herb@google.com
Bug: skia:6898
Change-Id: I91c62df5470acbf5c0acf0c558d2d5d3bf48d40e
Reviewed-on: https://skia-review.googlesource.com/98682
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Herb Derby <herb@google.com>
1 file changed