getopt return value changed from char to int (https://github.com/clicon/clixon/issues/58)

apps/backend/backend_main.c

@@ -504,7 +504,7 @@ main(int    argc,
      char **argv)
 {
     int           retval = -1;
-    char          c;
+    int           c;
     int           zap;
     int           foreground;
     int           once;

apps/cli/cli_main.c

@@ -240,7 +240,7 @@ int
 main(int argc, char **argv)
 {
     int          retval = -1;
-    char         c;    
+    int          c;    
     int          once;
     char	*tmp;
     char	*argv0 = argv[0];

apps/netconf/netconf_main.c

@@ -330,7 +330,7 @@ int
 main(int    argc,
      char **argv)
 {
-    char             c;
+    int              c;
     char            *tmp;
     char            *argv0 = argv[0];
     int              quiet = 0;

apps/restconf/restconf_main.c

@@ -513,7 +513,7 @@ main(int    argc,
     char	 *argv0 = argv[0];
     FCGX_Request  request;
     FCGX_Request *r = &request;
-    char          c;
+    int           c;
     char         *sockpath;
     char         *path;
     clicon_handle h;