radv: Use secure_getenv in radv_builtin_cache_path

Reviewed-by: Eric Engestrom <eric@igalia.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27381>
(cherry picked from commit c01a07f2e4)

.pick_status.json

@@ -54,7 +54,7 @@
         "description": "radv: Use secure_getenv in radv_builtin_cache_path",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null

src/amd/vulkan/meta/radv_meta.c

@@ -296,7 +296,7 @@ meta_free(void *_device, void *data)
 static bool
 radv_builtin_cache_path(char *path)
 {
-   char *xdg_cache_home = getenv("XDG_CACHE_HOME");
+   char *xdg_cache_home = secure_getenv("XDG_CACHE_HOME");
    const char *suffix = "/radv_builtin_shaders";
    const char *suffix2 = "/.cache/radv_builtin_shaders";
    struct passwd pwd, *result;