DBI->trace treats class name as hash reference

[fglock]

Summary

PerlOnJava cannot call the DBI class method DBI->trace(0). It treats the
class name string ("DBI") as though it were a database-handle hash
reference. This prevents distributions that disable DBI tracing during
initialization from loading at all.

Reproduction

Run either backend:

./jperl -MDBI -e 'DBI->trace(0); print "ok\\n"'
./jperl --interpreter -MDBI -e 'DBI->trace(0); print "ok\\n"'

Expected output:

ok

Actual result on both backends:

Can't use string ("DBI") as a HASH ref while "strict refs" in use at jar:PERL5LIB/DBI.pm line 1355.

The same call succeeds under system Perl with DBI 1.651.

CPAN failure that exposed the bug

The CPAN random-tester run 20260910-101908-8428 reported FAIL for
DBIx::PhraseBook 1.003. Its test file loads DBIx::PhraseBook, whose
INIT block calls:

DBI->trace(0);

The test process aborts before the first assertion, producing zero tests:

t/DBIx-PhraseBook.t (Wstat: 65280) ...
Tests: 0 Failed: 0
Result: FAIL

This is not a DBIx::PhraseBook-specific operation; the minimal DBI
reproducer fails without that distribution and on both PerlOnJava execution
backends.

Technical evidence

The bundled Perl implementation of DBI::trace currently begins with:

sub trace {
    my ($dbh, $level, $output) = @_;
    $level ||= 0;
    $dbh->{TraceLevel} = $level;
    ...
}

For a class-method invocation, $dbh is the string "DBI". Standard DBI
accepts DBI->trace(...) as a package-level tracing operation, so the
implementation needs to distinguish class-level invocation from a
database-handle invocation, or otherwise provide compatible class-method
semantics.

Impact

Any CPAN module that calls DBI->trace(...) during module initialization can
fail to compile or load under PerlOnJava. This also masks the module's own
tests, as demonstrated by DBIx::PhraseBook.

Suggested regression coverage

Add a project-owned test that invokes DBI->trace(0) under both backends and
asserts that it completes without a hash-reference error. Include at least
one class-level trace-setting case and preserve handle-level behavior if the
implementation shares the same method.