Third updated patch - this version also includes copyright notice in added Perl script.
This patch implements a check for such modules at runtime. If modules are not found or unable to load, the test is skipped with 
the following message:
            
            [ skipped ]  Test needs Perl modules DBI and DBD::mysql
            
Checks are done via a helper Perl script which looks for the module in a runtime environment that is as similar to that of the 
mysqlhotcopy script as possible (thus not intended for Windows environments at this time).
The helper script tells mysql-test about the result by writing information to a temporary file that is later read by mysql-test.
See comments in added files (have_dbi_dbd-mysql.inc and checkDBI_DBD-mysql.pl) for details.
The patch also removes the mysqlhotcopy tests from the list of disabled tests.