QbsProjectManager: Do not enable "check timestamp" option by default.

This is a workaround for user mistakes and should not be generally done.
It can result in e.g. redundant relinking.

Change-Id: Ia14854c9d260f5d7a8175d105b9bce896fcdeebf
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/plugins/qbsprojectmanager/qbsbuildstep.cpp

@@ -199,7 +199,7 @@ bool QbsBuildStep::fromMap(const QVariantMap &map)
     setQbsConfiguration(map.value(QLatin1String(QBS_CONFIG)).toMap());
     m_qbsBuildOptions.setDryRun(map.value(QLatin1String(QBS_DRY_RUN)).toBool());
     m_qbsBuildOptions.setKeepGoing(map.value(QLatin1String(QBS_KEEP_GOING)).toBool());
-    m_qbsBuildOptions.setForceTimestampCheck(map.value(QLatin1String(QBS_CHECK_TIMESTAMPS), true).toBool());
+    m_qbsBuildOptions.setForceTimestampCheck(map.value(QLatin1String(QBS_CHECK_TIMESTAMPS)).toBool());
     m_qbsBuildOptions.setMaxJobCount(map.value(QLatin1String(QBS_MAXJOBCOUNT)).toInt());
     return true;
 }