Remove redundant old isatty.c since newer termios supplies one.

libc/sysdeps/linux/common/Makefile

@@ -28,7 +28,7 @@ LIBC=$(TOPDIR)libc.a
 CSRC=	_xmknod.c waitpid.c getdents.c kernel_version.c rewinddir.c \
 	statfix.c getdnnm.c seekdir.c telldir.c tell.c gethstnm.c \
 	mkfifo.c setegid.c wait.c errno.c closedir.c getpagesize.c \
-	opendir.c seteuid.c wait3.c dirfd.c isatty.c readdir.c setpgrp.c \
+	opendir.c seteuid.c wait3.c dirfd.c readdir.c setpgrp.c \
 	getdtablesize.c
 
 COBJS=$(patsubst %.c,%.o, $(CSRC))