Fix coercion of floats to integer for %d printf specifier

Fixes JuliaLang#37507. The issue here was the calling of `trunc` instead of
`round` when coercing `AbstractFloat` arguments to `Integer`. Note this
throws a scary warning and has undefined behavior in C, but it looks
like legacy Printf code supported this, so we can try to do the right
thing here. Previously, Printf called the grisu equivalent of
`Ryu.writefixed(x, precision=0)` for float arguments, but as far as I
can tell, calling `round(x)` should accomplish the same thing.

stdlib/Printf/src/Printf.jl

@@ -266,7 +266,7 @@ end
  leftalign, plus, space, zero, hash, width, prec =
  spec.leftalign, spec.plus, spec.space, spec.zero, spec.hash, spec.width, spec.precision
  bs = base(T)
- arg2 = arg isa AbstractFloat ? Integer(trunc(arg)) : arg
+ arg2 = arg isa AbstractFloat ? Integer(round(arg)) : arg
  n = i = ndigits(arg2, base=bs, pad=1)
  x, neg = arg2 < 0 ? (-arg2, true) : (arg2, false)
  arglen = n + (neg || (plus | space)) +
@@ -675,7 +675,7 @@ function plength(f::Spec{T}, x) where {T <: Strings}
 end
 
 function plength(f::Spec{T}, x) where {T <: Ints}
- x2 = x isa AbstractFloat ? Integer(trunc(x)) : x
+ x2 = x isa AbstractFloat ? Integer(round(x)) : x
  return max(f.width, f.precision + ndigits(x2, base=base(T), pad=1) + 5)
 end
 

stdlib/Printf/test/runtests.jl

@@ -423,6 +423,8 @@ end
  @test_throws ArgumentError @sprintf("%s%%%s", "a")
  @test @sprintf("%s%%%s", "a", "b") == "a%%b"
 
+ # print float as %d uses round(x)
+ @test @sprintf("%d", 25.5) == "26"
 end
 
 @testset "integers" begin