azure: Add workaround for PhantomJS against OpenSSL 1.1.1

WebUI unit tests fail with:
```
PhantomJS threw an error:ERROR
>> Auto configuration failed 0 [
>>   'Auto configuration failed',
>>   '140613066520384:error:25066067:DSO support routines:DLFCN_LOAD:could not load the shared library:dso_dlfcn.c:185:filename(libssl_conf.so): libssl_conf.so: cannot open shared object file: No such file or directory',
>>   '140613066520384:error:25070067:DSO support routines:DSO_load:could not load the shared library:dso_lib.c:244:',
>>   '140613066520384:error:0E07506E:configuration file routines:MODULE_LOAD_DSO:error loading dso:conf_mod.c:285:module=ssl_conf, path=ssl_conf',
>>   '140613066520384:error:0E076071:configuration file routines:MODULE_RUN:unknown module name:conf_mod.c:222:module=ssl_conf'
>> ]
...

Warning: PhantomJS exited unexpectedly with exit code 1.� Use --force to continue.

Aborted due to warnings.
```

See wch/webshot#93 for details.

ipatests/azure/azure-pipelines.yml

@@ -126,6 +126,9 @@ jobs:
     - script: |
         set -e
         echo "Running WebUI unit tests"
+        # PhantomJS is not compatible with OpenSSL 1.1.1
+        # https://github.com/wch/webshot/pull/93
+        export OPENSSL_CONF=whatever
         cd $(builddir)/install/ui/js/libs && make
         cd $(builddir)/install/ui && npm install
         cd $(builddir)/install/ui && node_modules/grunt/bin/grunt --verbose test