Fix installer deleting nsclient.ini on upgrade

The PurgeConfig component carried a `<RemoveFile Name="*.ini"
On="uninstall"/>` rule whose glob also matches the user's nsclient.ini.
Because RemoveFile entries are name-based and bypass MSI component
reference counting, that rule deletes nsclient.ini whenever the
component is removed - including when RemoveExistingProducts uninstalls
the previous version during a major upgrade. With RemoveExistingProducts
scheduled After InstallExecute (late), this fires after BackupConfig /
ExecWriteConfig have already restored the configuration, so the
just-restored nsclient.ini is deleted and NeverOverwrite on the config
component prevents a fresh copy from being laid down.

The `NOT OLDERVERSIONBEINGUPGRADED` guard on the component does not help:
a component whose <Condition> evaluates false is set to absent, and an
On="uninstall" RemoveFile fires exactly when the component goes absent -
so gating the purge off during upgrade actually triggers it.

There is no purely declarative way for an On="uninstall" RemoveFile to
distinguish a real uninstall from the upgrade-time removal of the old
product, and NSClient++ already goes to some length (BackupConfig /
ExecWriteConfig) to preserve configuration across upgrades. Removing the
component keeps nsclient.ini intact on upgrade. If purge-on-real-uninstall
is wanted later it should be a deferred custom action gated on
REMOVE="ALL" AND NOT UPGRADINGPRODUCTCODE.

Signed-off-by: Michael Medin <michael@medin.name>

Author: mickem

installers/installer-NSCP/Product.wxs

@@ -70,12 +70,6 @@
             </File>
             <Condition>USER_WRITABLE_CONFIG AND NOT ALLOW_CONFIGURATION="0"</Condition>
           </Component>
-          <Component Id="PurgeConfig" Guid="E5A2F1C3-9B84-4D67-A1E0-3C7F28D59B12" Win64="$(var.Win64)">
-            <RegistryValue Root="HKCU" Key="Software\NSClient++\Installer" Name="purge config" Type="integer" Value="1" KeyPath="yes"/>
-            <RemoveFile Id="PurgeConfigFiles" Name="*.ini" On="uninstall" />
-            <Condition>NOT ALLOW_CONFIGURATION="0" AND NOT OLDERVERSIONBEINGUPGRADED</Condition>
-          </Component>
-
           <Component Id="RandomFiles" Guid="E23865C3-C11F-4d11-BE63-C670D60B0CD0" Win64="$(var.Win64)">
             <File Id="License" Name="license.txt" DiskId="1" Source="$(var.Source)/license.txt" Vital="no" KeyPath="yes" />
             <File Id="settingsMap" Name="old-settings.map" DiskId="1" Source="$(var.Source)/old-settings.map" Vital="no" />
@@ -216,7 +210,6 @@
 
         <ComponentRef Id="NSClientConfig" />
         <ComponentRef Id="NSClientConfigUser" />
-        <ComponentRef Id="PurgeConfig" />
 
         <?if "$(var.Runtime)" = "dynamic"?>
         <MergeRef Id="VCRedist110"/>