appveyor build fails due to openssl error

[mike10004]

When you run AutoCertificateAndKeySourceTest, openssl exits with status 1 and

Error outputting keys and certificates
2368:error:0907E06F:PEM routines:do_pk8pkey:read key:crypto/pem/pem_pk8.c:83:

is printed on stderr.

This is in the step where we produce a PEM file from a PKCS12 file.

This can be reproduced with the openssl executable version 1.1.0f from Strawberry Perl 5.26.1.1. On my local machine I can successfully generate the PEM file with OpenSSL 1.0.1h, from an earlier Strawberry Perl.

The same error occurs with the openssl.light package version 1.1.0.60000000 from Chocolatey.

Currently we just skip that step (and skip installing Strawberry Perl at all) in the appveyor configuration.