DSL ReleaseProgram retains source and reports errors better

Change-Id: Id5923e1c1404bddf7f7da7d04bd91721ab637322
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/429096
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
3 files changed