It looks like commit 30b9c6a4 made
this obsolete: by default, curl's configure will pick some OpenSSL
certificate database in /etc to use, which is in PEM format.

But since every distribution uses a different path in /etc for that,
it will work only on the same distribution as the build host anyway,
which makes it mostly useless in practice.

So we don't need our NSS to be able to read PEM format now.

Speaking of which, PEM support was only required for Linux builds
anyway, not for WNT/Mac builds.

Change-Id: Ib9bc6ec0b7d71c14e9a53454e6efed038072e913
Reviewed-on: https://gerrit.libreoffice.org/23435Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Giuseppe Castagno <giuseppe.castagno@acca-esse.eu>
Reviewed-by: Michael Stahl <mstahl@redhat.com>