Fix for gcc 10

Gcc 10 defaults to -fno-common, leading to multiple global definitions
to cause a linker error.

dpid/dpid.h

@@ -25,10 +25,10 @@
 
 /*! \TODO: Should read this from dillorc */
 #define SRS_NAME "dpid.srs"
-char *srs_name;
+extern char *srs_name;
 
 /*! dpid's service request socket file descriptor */
-int srs_fd;
+extern int srs_fd;
 
 /*! plugin state information
  */
@@ -49,19 +49,19 @@ struct service {
 };
 
 /*! Number of available plugins */
-int numdpis;
+extern int numdpis;
 
 /*! Number of sockets being watched */
-int numsocks;
+extern int numsocks;
 
 /*! State information for each plugin. */
-struct dp *dpi_attr_list;
+extern struct dp *dpi_attr_list;
 
 /*! service served for each plugin  */
-Dlist *services_list;
+extern Dlist *services_list;
 
 /*! Set of sockets watched for connections */
-fd_set sock_set;
+extern fd_set sock_set;
 
 /*! Set to 1 by the SIGCHLD handler dpi_sigchld */
 extern volatile sig_atomic_t caught_sigchld;

dpid/dpid_common.h

@@ -35,12 +35,9 @@
 #define CKD_WRITE(fd, msg) ckd_write(fd, msg, __FILE__, __LINE__)
 #define CKD_CLOSE(fd)      ckd_close(fd, __FILE__, __LINE__)
 
-
 /*! Error codes for dpid */
-enum {
-   no_errors,
-   dpid_srs_addrinuse /* dpid service request socket address already in use */
-} dpi_errno;
+//fix for gcc 10
+extern enum  dpi_errno;
 
 /*! Intended for identifying dillo plugins
  * and related files

dpid/main.c

@@ -1,5 +1,7 @@
 /*
    Copyright (C) 2003  Ferdi Franceschini <[email protected]>
+                 2020  Axel Beckert <[email protected]>
+                 2023  Michal Grezl <[email protected]>
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -32,6 +34,24 @@
 
 sigset_t mask_sigchld;
 
+/* fix for gcc 10 */
+
+enum {
+   no_errors,
+   dpid_srs_addrinuse /* dpid service request socket address already in use */
+} dpi_errno;
+
+char *srs_name;
+int numdpis;
+fd_set sock_set;
+struct dp *dpi_attr_list;
+Dlist *services_list;
+int numsocks;
+int srs_fd;
+;
+
+// end of fix
+
 
 /* Start a dpi filter plugin after accepting the pending connection
  * \Return