1.12 bugfix: unset local var to prevent env influence

[Thien-Thi Nguyen]

Automake 1.12 "make check" reported only one FAIL, which
i traced to a strange value for var 'd' in t/remake11.sh,
leaking in from the environment.  You can probably guess
its value from this test-suite.log excerpt:

test-suite.log-EXCERPT
Description: Binary data

Anyway, here's the trivial patch:

remake11.sh.diff
Description: Text Data

and a suitable ChangeLog entry:

        tests: unset local var to prevent env influence

        * t/remake11.sh: Unset 'd' before first use.

Probably the entire suite should be audited for this class of bug.
Anyway, now i can happily move on to "make install"...