Making njs_value_property_i64() and njs_value_property_i64_set() fast.
Making njs_value_property_i64() and njs_value_property_i64_set() fast.

Since f5afb325896f (0.3.9) njs_value_property() and
njs_value_property_set() have fast paths when key is a number.

Passing key as a number eliminates conversion index to string and back.

nginx/njs,nginx/njs,nginx/njs,nginx/njs,nginx/njs,nginx/njs