Use ints instead of floats for usage values

Author: Lillian Zhang

src/main/ruby/truffleruby/core/gc.rb

@@ -85,18 +85,18 @@ def self.stat(option = nil)
       :minor_gc_count => minor_count,
       :major_gc_count => major_count,
       :unknown_count => unknown_count, # if nonzero, major or minor count needs to be updated for this GC case
-      :committed => 0.0,
-      :init => 0.0,
-      :max => 0.0,
-      :used => 0.0,
-      :peak_committed => 0.0,
-      :peak_init => 0.0,
-      :peak_max => 0.0,
-      :peak_used => 0.0,
-      :last_committed => 0.0,
-      :last_init => 0.0,
-      :last_max => 0.0,
-      :last_used => 0.0,
+      :committed => 0,
+      :init => 0,
+      :max => 0,
+      :used => 0,
+      :peak_committed => 0,
+      :peak_init => 0,
+      :peak_max => 0,
+      :peak_used => 0,
+      :last_committed => 0,
+      :last_init => 0,
+      :last_max => 0,
+      :last_used => 0,
       :heap_available_slots => committed, # should be the same as the calculated committed
       :heap_live_slots => used, # should be the same as the calculated used
       :heap_free_slots => committed - used,