i#2861 cronbuilds: Set custom version from tag on Appveyor

We trigger a custom build by setting VERSION_NUMBER in Travis.
But Appveyor does not have access to that.
Here we extract that number from the git tag that the Travis build set.

Issue: #2861

suite/runsuite_wrapper.pl

@@ -90,6 +90,11 @@
          $ENV{'APPVEYOR_REPO_TAG'} eq 'true') {
     # A package build.
     my $build = "0";
+    # We trigger by setting VERSION_NUMBER in Travis.
+    # That sets a tag and we propagate the name into the Appveyor build from the tag:
+    if ($ENV{'APPVEYOR_REPO_TAG_NAME'} =~ /release_(.*)/) {
+        $ENV{'VERSION_NUMBER'} = $1;
+    }
     if ($ENV{'VERSION_NUMBER'} =~ /-(\d+)$/) {
         $build = $1;
     }