unix: fix integer overflow in uv_hrtime
unix: fix integer overflow in uv_hrtime

Conversion to nanoseconds was overflowing with 32-bit builds.

Taken from
https://github.com/joyent/libuv/commit/ce87b7e14cbf886e0f2279a322b87267a73071a0

ichramm/LuaNode,ichramm/LuaNode,ignacio/LuaNode,ichramm/LuaNode,ignacio/LuaNode,ignacio/LuaNode,ignacio/LuaNode,ichramm/LuaNode