[evince] synctex: Fix compilation

[Germán Poo-Caamaño <gpoo src gnome org>]

commit dab0dc31dba530b7c5d92122cd2047e0f3f97452
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Wed Jul 11 00:46:06 2018 -0400

    synctex: Fix compilation
    
    Default synctex does not build on Evince. Add declaration
    of missing prototypes, and define #_GNU_SOURCE to use
    vasprintf from stdio.

 cut-n-paste/synctex/synctex_parser.c       | 7 +++++++
 cut-n-paste/synctex/synctex_parser_utils.c | 2 ++
 2 files changed, 9 insertions(+)
---
diff --git a/cut-n-paste/synctex/synctex_parser.c b/cut-n-paste/synctex/synctex_parser.c
index f4f7d848..a613f35a 100644
--- a/cut-n-paste/synctex/synctex_parser.c
+++ b/cut-n-paste/synctex/synctex_parser.c
@@ -95,6 +95,7 @@
 #       endif
 #   endif
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -262,6 +263,8 @@ typedef synctex_node_p synctex_noxy_p;
 #       pragma mark Abstract OBJECTS and METHODS
 #   endif
 
+void synctex_node_free(synctex_node_p node);
+
 /**
  *  \def SYNCTEX_MSG_SEND
  *  \brief Takes care of sending the given message if possible.
@@ -533,6 +536,10 @@ typedef struct {
     synctex_io_mode_t io_mode;
 } synctex_open_s;
 
+void synctex_reader_free(synctex_reader_p reader);
+synctex_reader_p synctex_reader_init_with_output_file(synctex_reader_p reader, const char * output, const 
char * build_directory);
+synctex_node_p _synctex_node_next(synctex_node_p node);
+
 /*     This functions opens the file at the "output" given location.
  *  It manages the problem of quoted filenames that appear with pdftex and filenames containing the space 
character.
  *  In TeXLive 2008, the synctex file created with pdftex did contain unexpected quotes.
diff --git a/cut-n-paste/synctex/synctex_parser_utils.c b/cut-n-paste/synctex/synctex_parser_utils.c
index c4f200d8..6580d389 100644
--- a/cut-n-paste/synctex/synctex_parser_utils.c
+++ b/cut-n-paste/synctex/synctex_parser_utils.c
@@ -87,6 +87,8 @@ void _synctex_free(void * ptr) {
 #   include <syslog.h>
 #endif
 
+int _synctex_log(int level, const char * prompt, const char * reason,va_list arg);
+
 int _synctex_log(int level, const char * prompt, const char * reason,va_list arg) {
        int result;
 #      ifdef SYNCTEX_RECENT_WINDOWS