Get sdktools and sdkhooks/dhooks to load on hl2sdk-mock (#1892)

* Build SDKTools for hl2sdk-mock

* Fix loading of extensions using advanced naming scheme for hl2sdk-mock

* Fix error on missing sv_visiblemaxplayers convar

* Build SDKHooks for hl2sdk-mock

* Fix x86_64 SourcePawn VM filename

* SDKHooks: Ignore missing IEntityListeners list in hl2sdk-mock

extensions/sdkhooks/AMBuilder

@@ -12,8 +12,6 @@ project.sources += [
 
 for sdk_name in SM.sdks:
   sdk = SM.sdks[sdk_name]
-  if sdk.name == 'mock':
-    continue
 
   for cxx in builder.targets:
     if not cxx.target.arch in sdk.platformSpec[cxx.target.platform]: