Fix build failure caused by use of the deprecated readdir_r(3) while
building with -Werror=deprecated-declarations

Patch copied from upstream source repository:
https://github.com/daveol/ola/commit/9d8575ff38f76df698ea8889e07a3dee8f21bd68

From 9d8575ff38f76df698ea8889e07a3dee8f21bd68 Mon Sep 17 00:00:00 2001
From: Dave Olsthoorn <dave.olsthoorn@gmail.com>
Date: Wed, 2 Mar 2016 11:22:17 +0100
Subject: [PATCH] Use readdir instead of readdir_r

This replacec the use of readdir_r with readdir since readdir seems to
be both dangarous and deprecated in newer versions of glibc.

This fixes #1055
---
 common/file/Util.cpp | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/common/file/Util.cpp b/common/file/Util.cpp
index e2261fd..0ffddd3 100644
--- a/common/file/Util.cpp
+++ b/common/file/Util.cpp
@@ -128,30 +128,29 @@ bool FindMatchingFiles(const string &directory,
   FindClose(h_find);
 #else
   DIR *dp;
-  struct dirent dir_ent;
-  struct dirent *dir_ent_p;
+  struct dirent *dir_ent;
   if ((dp = opendir(directory.data())) == NULL) {
     OLA_WARN << "Could not open " << directory << ":" << strerror(errno);
     return false;
   }
 
-  if (readdir_r(dp, &dir_ent, &dir_ent_p)) {
-    OLA_WARN << "readdir_r(" << directory << "): " << strerror(errno);
+  if ((dir_ent = readdir(dp)) == NULL) {
+    OLA_WARN << "readdir(" << directory << "): " << strerror(errno);
     closedir(dp);
     return false;
   }
 
-  while (dir_ent_p != NULL) {
+  while (dir_ent != NULL) {
     vector<string>::const_iterator iter;
     for (iter = prefixes.begin(); iter != prefixes.end(); ++iter) {
-      if (!strncmp(dir_ent_p->d_name, iter->data(), iter->size())) {
+      if (!strncmp(dir_ent->d_name, iter->data(), iter->size())) {
         std::ostringstream str;
-        str << directory << PATH_SEPARATOR << dir_ent_p->d_name;
+        str << directory << PATH_SEPARATOR << dir_ent->d_name;
         files->push_back(str.str());
       }
     }
-    if (readdir_r(dp, &dir_ent, &dir_ent_p)) {
-      OLA_WARN << "readdir_r(" << directory << "): " << strerror(errno);
+    if ((dir_ent = readdir(dp)) == NULL) {
+      OLA_WARN << "readdir(" << directory << "): " << strerror(errno);
       closedir(dp);
       return false;
     }
/<a href='/guix/log/gnu/packages/gv.scm?id=31a7ef7091ebbdf69525481c5208579ad1eb35bc'>gv.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/gv.scm?id=31a7ef7091ebbdf69525481c5208579ad1eb35bc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-03-30 01:30:16 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/gv.scm?id=6fd52309b8f52c9bb59fccffac53e029ce94b698'>gnu: Use HTTPS for almost all gnu.org HOME-PAGEs.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-01-05 23:45:38 +0100'>2017-01-05</span></td><td><a href='/guix/commit/gnu/packages/gv.scm?id=fbec5abeef78ee52a56e3cd2183fd34baec47773'>gnu: gv: Do not propagate Ghostscript.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-09-02 14:35:40 +0300'>2016-09-02</span></td><td><a href='/guix/commit/gnu/packages/gv.scm?id=fb0b9ff1fabb3106ff72f3fe5f531b14f96bda8d'>gnu: Use ghostscript over ghostscript-gs.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2016-07-25 11:37:43 +0200'>2016-07-25</span></td><td><a href='/guix/commit/gnu/packages/gv.scm?id=d8eb912132ccdff955e3318fe549c5f7f674adf8'>gnu: Use 'ghostscript-gs' in packages that need the 'gs' command.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2015-08-08 14:09:56 -0400'>2015-08-08</span></td><td><a href='/guix/commit/gnu/packages/gv.scm?id=7a75b02ae54b054cdc614d1cb5af7ed26c4f63c3'>gnu: Move ghostscript-with-x into (gnu packages ghostscript).</a><span class='msg-avail'>...</span></td><td>Mark H Weaver</td></tr>