systemc: Handle integer based IDs like Accellera does.

systemc: Handle integer based IDs like Accellera does.

This is actually not consistent with how it was handled in 2.0.1 which
is supposedly what this is supposed to be backwards compatible with,
in that in the earlier version on info and warning messages were
suppressed. This is exposed by one of the tests,
utils/sc_report/test01, which suppresses an integer ID and then reports
an error with it. The "golden" output shows the message supressed, but
the actual implementation makes no such distinction.

This implementation duplicates Accelleras for now, but a future change
will make it consistent with the old implementation so the test will
pass.

Change-Id: I8f959321151e2bb60b94000594f30531b80e2684
Reviewed-on: https://gem5-review.googlesource.com/c/13319
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>