ProjectExplorer: Replace the fromMap error return value

... by some out-of-band mechanism, keeping previous functionality.

The driving reason is to get the same fromMap signature as in the
AspectContainer base, however, the whole mechanism seems rather useless:
There are only a few places that actually ever could report errors,
in those places "moving on" looks ok, too, and these few places
are not conceptually different than a lot others.

Removal of this (new) mechanism is left for later.

Change-Id: Ibe7a0456bc3b84a84e942231f14446e783372d76
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/remotelinux/abstractremotelinuxdeploystep.cpp

@@ -82,12 +82,12 @@ void AbstractRemoteLinuxDeployStep::setInternalInitializer(
     d->internalInit = init;
 }
 
-bool AbstractRemoteLinuxDeployStep::fromMap(const QVariantMap &map)
+void AbstractRemoteLinuxDeployStep::fromMap(const QVariantMap &map)
 {
-    if (!BuildStep::fromMap(map))
-        return false;
+    BuildStep::fromMap(map);
+    if (hasError())
+        return;
     d->deployTimes.importDeployTimes(map);
-    return true;
 }
 
 void AbstractRemoteLinuxDeployStep::toMap(QVariantMap &map) const