Fix check to enable perl5 tests

[AMDmi3]

Summary

Instead of NO_PERL5_TEST which duplicates NO_TEST, a check should be added to perl5.mk to only enables perl5 tests if perl5 build is used

Test Plan

Tested on ftp/curl

[mat]

[mat]

Actually, it may maybe be better to add a USE_PERL5=test thing, that would be added by the configure/modbuild* cases, would it not ?

[AMDmi3]

In D3830#79014, @mat wrote:

Actually, it may maybe be better to add a USE_PERL5=test thing, that would be added by the configure/modbuild* cases, would it not ?

What purpose will it serve? E.g. it has no meaning without configure/modbuild*.

[sunpoet]

Now I understand what you mean in previous mail. :)
Please commit.
Thanks!