kernel: file_wrapper: copy mode of original inode

Bionic uses fstat to determine whether an fd is a tty and set proper
buffering flags, so we also need to set the wrapper file's inode mode to
the original inode mode.

see:
https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/upstream-openbsd/lib/libc/stdio/makebuf.c;l=61-95;drc=9a4b68e20d617b2cb3355071521f16e8c3d538df

kernel/supercalls.c

@@ -399,6 +399,8 @@ static int do_get_wrapper_fd(void __user *arg) {
     struct file* pf = fget(ret);
 
     struct inode* wrapper_inode = file_inode(pf);
+    // copy original inode mode
+    wrapper_inode->i_mode = file_inode(f)->i_mode;
     struct inode_security_struct *sec = selinux_inode(wrapper_inode);
     if (sec) {
         sec->sid = ksu_file_sid;