PKG: set GENERATE_PACKAGE to ON when building directly from Packaging

SuperBuild/Packaging/CMakeLists.txt

@@ -16,6 +16,7 @@ option(GENERATE_XDK "Generate XDK for OTB development" OFF)
 set(OUT_OF_SOURCE_BUILD FALSE)
 if(PROJECT_NAME STREQUAL "OTBPackaging")
   set(OUT_OF_SOURCE_BUILD TRUE)
+  set(GENERATE_PACKAGE ON)
 endif()
 
 if(NOT GENERATE_PACKAGE AND NOT GENERATE_XDK)