Allow us to specify the typelib sysroot in wrapper scripts for cross compiling.

--- a/girepository/girepository.c
+++ b/girepository/girepository.c
@@ -154,6 +154,7 @@ gi_repository_init (GIRepository *reposi
       const char *libdir;
       char *typelib_dir;
       const char *type_lib_path_env;
+      const char *type_lib_sysroot_env;
 
       /* This variable is intended to take precedence over both:
        *   - the default search path;
@@ -161,6 +162,9 @@ gi_repository_init (GIRepository *reposi
        */
       type_lib_path_env = g_getenv ("GI_TYPELIB_PATH");
 
+      /* Void Linux addition for cross compiling, since we use cross sysroots */
+      type_lib_sysroot_env = g_getenv ("GI_TYPELIB_SYSROOT");
+
       if (type_lib_path_env)
         {
           char **custom_dirs;
@@ -176,7 +180,10 @@ gi_repository_init (GIRepository *reposi
 
       libdir = GOBJECT_INTROSPECTION_LIBDIR;
 
-      typelib_dir = g_build_filename (libdir, "girepository-1.0", NULL);
+      if (type_lib_sysroot_env)
+          typelib_dir = g_build_filename (type_lib_sysroot_env, libdir, "girepository-1.0", NULL);
+      else
+          typelib_dir = g_build_filename (libdir, "girepository-1.0", NULL);
 
       g_ptr_array_add (repository->typelib_search_path, g_steal_pointer (&typelib_dir));
     }