fixup! Add Fiber::Stack#size

Author: ysbaddaden

src/fiber/stack.cr

@@ -7,10 +7,8 @@ class Fiber
     getter? reusable : Bool
 
     def initialize(@pointer : Void*, @bottom : Void*, *, @reusable = false)
-      {% if flag?(:unix) %}
-        LibC.dprintf 2, "DEBUG: Fiber::Stack.new(%p, %p, %s)\n", @pointer, @bottom, @reusable ? "true" : "false"
-      {% end %}
-      @size = (@bottom - @pointer).to_i32
+      # NOTE: sometimes gc/boehm reports weird stacks on linux (over 2GB)
+      @size = (@bottom - @pointer).to_i32!
     end
 
     def initialize(@pointer : Void*, @size : Int32, *, @reusable = false)