Revert of Revert of Clean up libjingle.gyp and remove references to libpeer_target_ty...

Revert of Revert of Clean up libjingle.gyp and remove references to libpeer_target_type. (patchset #1 id:1 of https://codereview.chromium.org/1025003002/)

Reason for revert:
Relanding libjingle.gyp update that removes libpeer_target_type references.  The issue on Android has been fixed.

Original issue's description:
> Revert of Clean up libjingle.gyp and remove references to libpeer_target_type. (patchset #1 id:1 of https://codereview.chromium.org/1008023002/)
>
> Reason for revert:
> See if this caused errors on Android.
>
> Original issue's description:
> > Clean up libjingle.gyp and remove references to libpeer_target_type.
> > This variable isn't supported any longer.
> >
> > BUG=446865
> >
> > Committed: https://crrev.com/fd22585c501bdd46f0a511fa5346fc9be1b85f88
> > Cr-Commit-Position: refs/heads/master@{#321371}
>
> TBR=kjellander@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=446865
>
> Committed: https://crrev.com/5e83cd0937a248f3d544800797b0dcbcba6eb13b
> Cr-Commit-Position: refs/heads/master@{#321614}

TBR=kjellander@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=446865

Review URL: https://codereview.chromium.org/1007063003

Cr-Commit-Position: refs/heads/master@{#322232}