Merge branch 'macos10.15-compile-fixes' into 'master'

Compile fixes for macOS 10.15 and later

See merge request sane-project/frontends!8

sanei/sanei_init_debug.c

@@ -100,7 +100,8 @@ sanei_debug_msg
 
   if (max_level >= level)
     {
-      if ( 1 == isfdtype(fileno(stderr), S_IFSOCK) )
+      struct stat sb;
+      if ( 0 == fstat(fileno(stderr), &sb) && S_IFSOCK == (sb.st_mode & S_IFMT) )
         {
           msg = (char *)malloc (sizeof(char) * (strlen(be) + strlen(fmt) + 4));
           if (msg == NULL)