Silence LTO related compiler warning

Silence LTO related compiler warning

master-service-settings-cache.c: In function 'master_service_settings_cache_init_filter':
master-service-settings-cache.c:94:3: warning: 'error' may be used uninitialized in this function [-Wmaybe-uninitialized]
   94 |   i_error("master-service: cannot get filters: %s", error);
      |   ^
master-service-settings-cache.c:89:14: note: 'error' was declared here
   89 |  const char *error;
      |              ^

Gbp-Pq: Name Silence-LTO-related-compiler-warning.patch