Revert "[infra] Use wheezy sysroot for local builds on linux."
Revert "[infra] Use wheezy sysroot for local builds on linux."

This reverts commit 4678cdaa2441a5f61a6a56fb831e362bb9c7ef42.

Reason for revert: This broke gcc arm builds.

Original change's description:
> [infra] Use wheezy sysroot for local builds on linux.
> 
> I had though that this is how things already worked, but it wasn't.
> 
> Change-Id: Iaa6b4e7d9e791f3fad29431c5715fcb19df8a76b
> Reviewed-on: https://dart-review.googlesource.com/40840
> Reviewed-by: Siva Annamalai <asiva@google.com>
> Commit-Queue: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>

TBR=rmacnak@google.com,9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com,asiva@google.com

Change-Id: I013fe2d3736acdcb8ce7d1ec959419f20aa0aa54
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/41340
Reviewed-by: Zach Anderson <9f8b31e960a68dade71618f1ff6da6e23a1edfc9@google.com>

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