systemc: Switch to using predefined messages for utils.

Create and use predefined messages for utils which match the ones
Accellera uses.

Change-Id: I932b7206fc16181d01a0d5b7441ce617b30e5365
Reviewed-on: https://gem5-review.googlesource.com/c/13328
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/utils/SConscript

@@ -29,6 +29,7 @@ Import('*')
 
 if env['USE_SYSTEMC']:
     Source('functions.cc')
+    Source('messages.cc')
     Source('report.cc')
     Source('sc_report.cc')
     Source('sc_report_handler.cc')