Fix #40318 by using UInt to convert instead of Int on Ptr

(cherry picked from commit 0d9163b)

Author: quinnj

stdlib/Printf/src/Printf.jl

@@ -547,7 +547,7 @@ const __BIG_FLOAT_MAX__ = 8192
 end
 
 # pointers
-fmt(buf, pos, arg, spec::Spec{Pointer}) = fmt(buf, pos, Int(arg), ptrfmt(spec, arg))
+fmt(buf, pos, arg, spec::Spec{Pointer}) = fmt(buf, pos, UInt(arg), ptrfmt(spec, arg))
 
 # old Printf compat
 function fix_dec end

stdlib/Printf/test/runtests.jl

@@ -19,6 +19,9 @@ using Test, Printf
         @test (@sprintf "%-20p" C_NULL) == "0x00000000          "
     end
 
+    #40318
+    @test @sprintf("%p", 0xfffffffffffe0000) == "0xfffffffffffe0000"
+
 end
 
 @testset "%a" begin