Evaluation of undeclared variable in get_site_option

[niallkennedy]

If the get_site_option function operates in a multisite environment with a use_cache parameter of false then $value will be undeclared and therefore not match a strict comparison of false.

Current code assumes $value will be set to false based on a wp_cache_get call that never happens.

Fix:
If $value is never set treat as if it was false.

[niallkennedy]

check if $value is undeclared

[nacin]

[14101]

[ryan]

That commit should be props niallkennedy. My bad.