Give the _ssl project a harmless command to perform

for its "clean" action.  Else the clean step run by
the buildbot reports failure, due to the _ssl project
whining about not being able to spawn an empty string.

PCbuild/_ssl.vcproj

@@ -3,6 +3,7 @@
 	ProjectType="Visual C++"
 	Version="7.10"
 	Name="_ssl"
+	RootNamespace="_ssl"
 	SccProjectName=""
 	SccLocalPath=""
 	Keyword="MakeFileProj">
@@ -22,6 +23,7 @@
 				Name="VCNMakeTool"
 				BuildCommandLine="python build_ssl.py"
 				ReBuildCommandLine="python build_ssl.py -a"
+				CleanCommandLine="echo Nothing to do"
 				Output="_ssl.pyd"/>
 		</Configuration>
 		<Configuration
@@ -35,6 +37,7 @@
 				Name="VCNMakeTool"
 				BuildCommandLine="python_d -u build_ssl.py -d"
 				ReBuildCommandLine="python_d -u build_ssl.py -d -a"
+				CleanCommandLine="echo Nothing to do"
 				Output="_ssl_d.pyd"/>
 		</Configuration>
 		<Configuration