Define UPC_OFF_MAX and required minumum value

[Former user]

Originally reported on Google Code with ID 34 ``` This is in the spirit of issue #21 which proposes to add predefined macros (with minimum conforming values) for various implementation-specific limits, but applied to the optional UPC I/O library.

I propose to append the following text in a appropriate place to be decided: "The predefined-macro UPC_OFF_MAX shall give the maximum supported value of type upc_off_t, and shall be no smaller than 2147483647."

```

Reported by `[e-mail]` on 2012-05-22 03:22:56

[Former user]

Reported by `[e-mail]` on 2012-06-01 03:20:35 - Labels added: Spec-1.3

[Former user]

Reported by `[e-mail]` on 2012-06-01 06:08:53 - Labels added: Milestone-Spec-1.3 - Labels removed: Spec-1.3

[Former user]

``` Set default Consensus to "Low". ```

Reported by `gary.funck` on 2012-08-19 23:26:19 - Labels added: Consensus-Low

[Former user]

``` Change Status to New: Requires review. ```

Reported by `gary.funck` on 2012-08-19 23:37:41 - Status changed: `New`

[Former user]

``` This issue was Rejected by a consensus on the UPC spec working group conf call on 2012.09.21. ```

Reported by `[e-mail]` on 2012-09-21 21:16:09 - Status changed: `Rejected`