Small issue with kerberos tests

Hi!

Recently, I attempted to run the entire set of pg tests with

PG_TEST_EXTRA="kerberos ..." on NetBSD but encountered 

a problem. The kerberos/001_auth and 

libpq/005_negotiate_encryption.pl test failed with an incomprehensible 

message:

[01:55:38.737](3.698s) # setting up Kerberos
# Running: krb5-config --version
Undefined subroutine &PostgreSQL::Test::Kerberos::BAIL_OUT called at /home/omg/proj/postgres/src/test/perl/PostgreSQL/Test/Kerberos.pm line 109.

The root cause of the problem was in using

------

$ /usr/bin/krb5-config --version
heimdal 7.8.0

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...insted of..

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$ /usr/pkg/bin/krb5-config --version
Kerberos 5 release 1.21.3

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In other words, PATH must be properly set to use Kerberos 5 version.

But, AFIACS, "use Test::More" is missing in Kerberos.pm resulting

in "Undefined subroutine" error instead of "Heimdal is not supported".