6640 dca gets the instance number a lot, never actually uses it

@@ -70,11 +70,10 @@
 LINTTAGS        += -erroff=E_BAD_PTR_CAST_ALIGN
 LINTTAGS        += -erroff=E_PTRDIFF_OVERFLOW
 LINTTAGS        += -erroff=E_ASSIGN_NARROW_CONV
 
 CERRWARN        += -_gcc=-Wno-parentheses
-CERRWARN        += -_gcc=-Wno-unused-variable
 
 #
 #       Default build targets.
 #
 .KEEP_STATE: