Add Racket support for std::unique_ptr and std::auto_ptr

Equivalent to Guile implementation.

Slight tweak to proxy ownership was required by adding in
the own member to swig_mz_proxy.

Examples/test-suite/mzscheme/newobject1_runme.scm

@@ -2,4 +2,8 @@
 
 (require (lib "defmacro.ss"))
 
+; Define an equivalent to Guile's gc procedure
+(define-macro (gc)
+  `(collect-garbage 'major))
+
 (load "../schemerunme/newobject1.scm")