gc.c: malloc_usable_size

* gc.c (vm_xrealloc, vm_xfree): use malloc_usable_size() to obtain old
  size if available.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43760 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_tempfile.rb: suppress warnings

* test/test_tempfile.rb (test_tempfile_is_unlinked_when_ruby_exits): no error should emit.

* test/test_tempfile.rb (test_tempfile_encoding_ascii8bit): remove unused variable.

* test/test_tempfile.rb (test_tempfile_encoding_ascii8bit2): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43761 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
gc.c: malloc_usable_size

* gc.c (malloc_usable_size): use _msize() on Windows.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43762 b2dd03c8-39d4-4d8f-98ff-823fe69b080e