Fix resuming external command run from 'eval' (re: 2c35a539)

'eval' suffers from the same bug. Reproducer:
    $ eval vi
then suspend vi, then try to resume it -- the same as in the
reproducer shown in the previous commit.

src/cmd/ksh93/bltins/misc.c: b_eval():
- Same fix. Do *not* turn off SH_MONITOR.

src/cmd/ksh93/bltins/misc.c

@@ -209,10 +209,7 @@ int    b_eval(int argc,char *argv[], Shbltin_t *context)
 	}
 	argv += opt_info.index;
 	if(*argv && **argv)
-	{
-		sh_offstate(SH_MONITOR);
 		sh_eval(sh_sfeval(argv),0);
-	}
 	return(sh.exitval);
 }