Ruby: fixed encodings initialization.

The Ruby interpreter expects an explicit setlocale() call before initialization
to pick up character encodings in the "Encoding" class from the environment.

This closes #531 issue on GitHub.

src/ruby/nxt_ruby.c

@@ -12,6 +12,8 @@
 
 #include NXT_RUBY_MOUNTS_H
 
+#include <locale.h>
+
 
 #define NXT_RUBY_RACK_API_VERSION_MAJOR  1
 #define NXT_RUBY_RACK_API_VERSION_MINOR  3
@@ -200,6 +202,8 @@ nxt_ruby_start(nxt_task_t *task, nxt_process_data_t *data)
 
     nxt_ruby_threads = c->threads;
 
+    setlocale(LC_CTYPE, "");
+
     RUBY_INIT_STACK
     ruby_init();
     ruby_options(2, argv);