The initial implementation of setPropByIndex() set the value of an Array
by index during development. Though the final form of the function
simply pushes passed values to an array as passed by arguments. Thus the
functions have been renamed to pushValueToArray() and
push_values_to_array_function() respectively.

Also add define for maximum number of arguments should be used before
hitting the limit of performance increase.

Fixes: 494227b "node: improve GetActiveRequests performance"

For performance add headers to the headers Array by pushing them on from
JS. Benchmark added to demonstrate this case.

Improve performance by pushing directory entries to returned array in
batches of 8 using pushValueToArray() in JS. Add benchmarks to
demonstrate this improvement.

Improve performance of process._getActiveHandles by sending handles in
batches to JS to be set on the passed Array. Add test to check proper
active handles are returned.

Alter implementation of GetActiveRequests to match GetActiveHandles'
implementation.

process.hrtime() was performing too many operations in C++ that could be
done faster in JS. Move those operations over by creating a length 4
Uint32Array and perform bitwise operations on the seconds so that it was
unnecessary for the native API to do any object creation or set any
fields.

This has improved performance from ~350 ns/op to ~65 ns/op. Light
benchmark included to demonstrate the performance change.

Set process.env array entries in JS.