qga: Installer: Wait for installation to finish

Installation might fail if we don't wait for the provider
unregisteration process to finish.

Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
Signed-off-by: Basil Salman <basil@daynix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

qga/installer/qemu-ga.wxs

@@ -81,7 +81,7 @@
               Arguments="-d --retry-path"
               >
             </ServiceInstall>
-            <ServiceControl Id="StartService" Start="install" Stop="both" Remove="uninstall" Name="QEMU-GA" Wait="no" />
+            <ServiceControl Id="StartService" Start="install" Stop="both" Remove="uninstall" Name="QEMU-GA" Wait="yes" />
           </Component>
           <?ifdef var.InstallVss?>
           <Component Id="qga_vss_dll" Guid="{CB19C453-FABB-4BB1-ABAB-6B74F687BFBB}">