[RDY] Include <stdint.h> in types.h and libuv's <stdint-msvc2008.h> for old MSVC

In short, this is PR #296 , but much less aggressive. I didn't redefine `long_u`, `long_i`... This would require changing many `printf`-style function calls to deal with the fact that long is 32-bits on Windows.

I replaced `UINT32_T` by `uint32_t`and deleted `UINT32_T` related code.

See my last comments there https://github.com/neovim/neovim/pull/296#issuecomment-37474283