Fix a memory lifetime bug in the ruby bindings.

* subversion/bindings/swig/ruby/libsvn_swig_ruby/swigutil_rb.c
  (svn_swig_rb_log_entry_receiver): Make a deep copy of the received log
   entry since it might be freed before all collected entries are processed. 

The ruby bindings tests were crashing while processing log entries
obtained from a call to svn_client_mergeinfo_log_merged().
Found by the bb-openbsd buildbot with APR pool debugging enabled.

Program received signal SIGBUS, Bus error.
0x000003f32550ff97 in apr_hash_first (p=0x0, ht=0x4141414141414141)
    at /home/stsp/svn/src/apr-1.5.0/tables/apr_hash.c:148
148         hi->ht = ht;

#3  0x000003f32dabe865 in svn_swig_rb_apr_hash_to_hash_swig_type (
    hash=0x4141414141414141, 
    type_name=0x3f32067ec0b "svn_log_changed_path_t *")
    at subversion/bindings/swig/ruby/libsvn_swig_ruby/swigutil_rb.c:1480



git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1586052 13f79535-47bb-0310-9956-ffa450edef68