Revert of Split src/opts source lists out of opts.gyp. (patchset #1 id:1 of https://codereview.chromium.org/870353003/)

Reason for revert:
Android Makefiles broken

Original issue's description:
> Split src/opts source lists out of opts.gyp.
>
> This should make it easier to keep our opts.gyp in sync with Chrome's GYP and GN.
>
> BUG=skia:
>
> Landing this without review as a mega-tryjob.
> TBR=reed@google.com
>
> Committed: https://skia.googlesource.com/skia/+/c98fe3aa4f8c97c462c0eb6d9106fc37e48d7f82

TBR=mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/880783002
3 files changed