meson: Fix linking using old OpenSSL lib names

meson: Fix linking using old OpenSSL lib names

Before OpenSSL 1.1.0 the legacy names ssleay32 and libeay32 were
still used on Windows, and while we have support for this auto-
conf the meson buildsystem only used the new names on all plat-
forms.  This adds support for the old name scheme when building
on Windows.

This patch only applies to 17 and 16 as master no longer support
OpenSSL 1.0.2.

Author: Darek Ślusarczyk <dslusarczyk@splunk.com>
Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAN55FZ1Nk8wqY=mTrN78H026TuGV50h2H6uq1PwxhTauPYi3ug@mail.gmail.com
Backpatch-through: 16