readdir.2: s/dirent/old_linux_dirent/

Nowadays, this is the name of the structure in the kernel sources.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/readdir.2

@@ -31,7 +31,7 @@ readdir \- read directory entry
 .SH SYNOPSIS
 .nf
 .sp
-.BI "int readdir(unsigned int " fd ", struct dirent *" dirp ","
+.BI "int readdir(unsigned int " fd ", struct old_linux_dirent *" dirp ","
 .BI "            unsigned int " count );
 .fi
 .SH DESCRIPTION
@@ -45,7 +45,7 @@ which is superseded by
 .PP
 .BR readdir ()
 reads one
-.I dirent
+.I old_linux_dirent
 structure from the directory
 referred to by the file descriptor
 .I fd
@@ -54,18 +54,18 @@ into the buffer pointed to by
 The argument
 .I count
 is ignored; at most one
-.I dirent
+.I old_linux_dirent
 structure is read.
 .PP
 The
-.I dirent
+.I old_linux_dirent
 structure is declared as follows:
 .PP
 .in +4n
 .nf
-struct dirent {
+struct old_linux_dirent {
     long     d_ino;               /* inode number */
-    off_t    d_off;               /* offset to this \fIdirent\fP */
+    off_t    d_off;               /* offset to this \fIold_linux_dirent\fP */
     unsigned short d_reclen;      /* length of this \fId_name\fP */
     char     d_name[NAME_MAX+1];  /* filename (null-terminated) */
 }
@@ -76,7 +76,7 @@ struct dirent {
 is an inode number.
 .I d_off
 is the distance from the start of the directory to this
-.IR dirent .
+.IR old_linux_dirent .
 .I d_reclen
 is the size of
 .IR d_name ,