base, sim, dev: Remove SWIG

Remove SWIG guards and SWIG-specific C++ code.

Change-Id: Icaad6720513b6f48153727ef3f70e0dba0df4bee
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2921
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Tony Gutierrez <anthony.gutierrez@amd.com>

ruby: replace Time with Cycles in Message class
Concomitant changes are being committed as well, including the io operator<<
for the Cycles class.