Perl 5.12 ships with a somewhat broken version of Test::Simple, so skip
the tests if that is found.
The relevant fix is
0.98 Wed, 23 Feb 2011 14:38:02 +1100
Bug Fixes
* subtest() should not fail if $? is non-zero. (Aaron Crane)
Unset environment variables that control message language, so that we
can compare some program output with expected strings. This is very
similar to what pg_regress does.
Creating the Unix-domain socket in the build directory can run into
name-length limitations. Therefore, create the socket file in the
default temporary directory of the operating system. Keep the temporary
data directory etc. in the build tree.
