Add a new statement type 'InlineMarker' to indicate inlined functions.

This will be leveraged in followup CLs to avoid recursive inlining death
spirals.

Change-Id: Icf99c88c4acaaa766e0dc0971830329e24d70509
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/315861
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
21 files changed