Fix MSVC warnings C4204 and C4244.
Fix MSVC warnings C4204 and C4244.

warning C4204: nonstandard extension used: non-constant aggregate
initializer
warning C4244: 'initializing': conversion from 'int32_t' to 'int16_t',
possible loss of data

Avoiding designated initializers also restores C++ compatibility.

ulfjack/ryu,ulfjack/ryu,ulfjack/ryu,ulfjack/ryu