remove usage of newfangled C++ that baseline toolchains don't support

--- poppler/goo/gfile.cc.orig	2019-01-16 11:02:21.112911552 +0100
+++ poppler/goo/gfile.cc	2019-01-16 11:01:33.125975178 +0100
@@ -67,7 +67,7 @@
 
 #ifndef _WIN32
 
-using namespace std::string_literals;
+//using namespace std::string_literals;
 
 namespace {
 
@@ -366,7 +366,7 @@
     }
 #else
     // First try to atomically open the file with CLOEXEC
-    const std::string modeStr = mode + "e"s;
+    const std::string modeStr = mode + std::string("e");
     FILE *file = fopen(path, modeStr.c_str());
     if (file != nullptr) {
         return file;
--- poppler/goo/gmem.h.orig	2019-01-16 11:25:28.161920038 +0100
+++ poppler/goo/gmem.h	2019-01-16 11:25:53.756882295 +0100
@@ -177,4 +177,6 @@
     return std::strncpy(r, s, n);
 }
 
+#include <o3tl/make_unique.hxx>
+
 #endif // GMEM_H
--- poppler/goo/gfile.cc.orig2	2022-09-15 12:33:24.163562177 +0200
+++ poppler/goo/gfile.cc	2022-09-15 12:33:49.501547336 +0200
@@ -50,6 +50,8 @@
 #include "gfile.h"
 #include "gdir.h"
 
+#include <o3tl/make_unique.hxx>
+
 // Some systems don't define this, so just make it something reasonably
 // large.
 #ifndef PATH_MAX