API param validation: Set strict mode for in_array

The in_array gives true when the allowed values contains a 0 as value,
for example by namespaces,

action=query&list=allpages&apnamespace=test|tset

was not rejected

Change-Id: I9220a955ffaf2bcb0d1d5b27c948af2f85714110
Merge "API param validation: Set strict mode for in_array"