base/write.jl: use s instead of t to satisfy @uv_write macro.

Fixes #3972. This was probably a typo in the function definitions
but having a blessed variable name like `s` seems a bit sketchy.

base/stream.jl

@@ -673,7 +673,7 @@ function _uv_hook_writecb(s::AsyncStream, req::Ptr{Void}, status::Int32)
 end
 
 # Do not task-block TTY methods. These writes are process-blocking anyway, so we use the non-copying versions
-write(t::TTY, b::Uint8) = @uv_write 1 ccall(:jl_putc_copy, Int32, (Uint8, Ptr{Void}, Ptr{Void}, Ptr{Void}), b, handle(s), uvw, uv_jl_writecb::Ptr{Void})
+write(s::TTY, b::Uint8) = @uv_write 1 ccall(:jl_putc_copy, Int32, (Uint8, Ptr{Void}, Ptr{Void}, Ptr{Void}), b, handle(s), uvw, uv_jl_writecb::Ptr{Void})
 write(s::TTY, c::Char) = @uv_write utf8sizeof(c) ccall(:jl_pututf8_copy, Int32, (Ptr{Void},Uint32, Ptr{Void}, Ptr{Void}), handle(s), c, uvw, uv_jl_writecb::Ptr{Void})
 function write{T}(s::TTY, a::Array{T}) 
     if isbits(T)