systemc: Enable systemc support by default.

Change-Id: I9375518a54e14413a499d065f5bc5e1031834c81
Reviewed-on: https://gem5-review.googlesource.com/c/13535
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
diff --git a/src/systemc/SConsopts b/src/systemc/SConsopts
index f3da63d..fc0abb2 100644
--- a/src/systemc/SConsopts
+++ b/src/systemc/SConsopts
@@ -28,7 +28,7 @@
 Import('*')
 
 sticky_vars.AddVariables(
-    BoolVariable('USE_SYSTEMC', 'Enable SystemC API support', False)
+    BoolVariable('USE_SYSTEMC', 'Enable SystemC API support', True)
     )
 
 export_vars.append('USE_SYSTEMC')