Revert of Use env variable if gyp_defines is not specified (patchset #2 id:20001 of https://codereview.chromium.org/1283153003/ )
Revert of Use env variable if gyp_defines is not specified (patchset #2 id:20001 of https://codereview.chromium.org/1283153003/ )

Reason for revert:
I suspect this is not needed. Trying out my suspicion.

Original issue's description:
> Use env variable if gyp_defines is not specified
>
> BUG=skia:
> TBR=benjaminwagner
>
> Committed: https://skia.googlesource.com/buildbot/+/5f78e02b4af577d1dfca9deeb0bab41e0d1c06cf

TBR=
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1283103004

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