darwin shared library patch

In Darwin, the preferred way to build shared libraries is with two level
namespaces. The following patch makes it possible to build the ruby shared
library in this fashion.

I would really like to see this integrated. This patch was created against
the 1.6 source. If a patch against the 1.7 source is needed, please let me
know.

diff -ruN ruby.orig/eval.c ruby/eval.c
--- ruby.orig/eval.c	Mon May 27 10:59:43 2002
+++ ruby/eval.c	Fri Oct 11 12:51:54 2002
@@ -23,6 +23,10 @@
 #include "st.h"
 #include "dln.h"
 
+#ifdef __APPLE__
+#include <crt_externs.h>
+#endif
+
 /* Make alloca work the best possible way.  */
 #ifdef __GNUC__
 # ifndef atarist
@@ -1008,6 +1012,8 @@
 
 #ifdef __MACOS__
     rb_origenviron = 0;
+#elif defined(__APPLE__)
+    rb_origenviron = *_NSGetEnviron();
 #else
     rb_origenviron = environ;
 #endif
diff -ruN ruby.orig/hash.c ruby/hash.c
--- ruby.orig/hash.c	Mon May 27 10:59:43 2002
+++ ruby/hash.c	Fri Oct 11 12:51:48 2002
@@ -17,6 +17,10 @@
 #include "util.h"
 #include "rubysig.h"
 
+#ifdef __APPLE__
+#include <crt_externs.h>
+#endif
+
 #define HASH_DELETED  FL_USER1
 
 static void
@@ -861,6 +865,11 @@
 static char **my_environ;
 #undef environ
 #define environ my_environ
+#elif defined(__APPLE__)
+#undef environ
+#define environ *_NSGetEnviron()
+#define GET_ENVIRON(e) (e)
+#define FREE_ENVIRON(e)
 #else
 extern char **environ;
 #define GET_ENVIRON(e) (e)