systemc: Stub out the sc_process_handle class.

Change-Id: I2250ccb369e0a5f2b9172d35662a9ce5e41ab1c1
Reviewed-on: https://gem5-review.googlesource.com/10836
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/SConscript

@@ -41,6 +41,7 @@ if env['USE_SYSTEMC']:
     Source('sc_module_name.cc')
     Source('sc_object.cc')
     Source('sc_port.cc')
+    Source('sc_process_handle.cc')
     Source('sc_prim.cc')
     Source('sc_sensitive.cc')
     Source('sc_time.cc')