Remove "XXX Giant" comments before calls to kdb_trap() -- the kernel

debugger is quite capable of handling Giant-free execution at this
point.  Several other similar comments remain in trap.c on both i386
and amd64 awaiting analysis.

sys/amd64/amd64/trap.c

@@ -468,7 +468,6 @@ trap(struct trapframe *frame)
 			 * Otherwise, debugger traps "can't happen".
 			 */
 #ifdef KDB
-			/* XXX Giant */
 			if (kdb_trap(type, 0, frame))
 				goto out;
 #endif

sys/i386/i386/trap.c

@@ -617,7 +617,6 @@ trap(struct trapframe *frame)
 			 * Otherwise, debugger traps "can't happen".
 			 */
 #ifdef KDB
-			/* XXX Giant */
 			if (kdb_trap(type, 0, frame))
 				goto out;
 #endif