Align the full version schema across all artifacts

Summary:
The version number used for packaging symbols and xswiftbus was not the
full one including the timestamp.
This change adds the last commit timestamp (in contrast to the build
timestamp used before) as regular part of the version number. This helps
us to also keep the version number consistent with the content across all
installers. The version number will change only, if the last commit was
modified and not with each different build.
In the end, all jenkins jobs building from the same commit should produce
artifacts with the same version everywhere.

ref T204

Reviewers: #swift_pilot_client, kbasan

Reviewed By: #swift_pilot_client, kbasan

Subscribers: jenkins

Maniphest Tasks: T204

Differential Revision: https://dev.swift-project.org/D68

src/blackmisc/db/distribution.cpp

@@ -253,10 +253,7 @@ namespace BlackMisc
                 return QVersionNumber::fromString(v);
             }
 
-            const QString versionTimestampString = BlackMisc::digitOnlyString(ts1Match.captured(0));
-            const QDateTime versionTimestamp = QDateTime::fromString(versionTimestampString, "yyyyMMddHHmmss");
-            const QString lastSegment = QString::number(CBuildConfig::buildTimestampAsVersionSegment(versionTimestamp));
-
+            const QString lastSegment = BlackMisc::digitOnlyString(ts1Match.captured(0));
             v += lastSegment;
             return QVersionNumber::fromString(v);
         }