Fixing HiPE bus errors on Mac OS X 10.5.3+, removes mach_override.

(should be compatible with Mac OS X >= 10.3, not compatible with Mac OS X 10.2 and earlier)

erts/emulator/Makefile.in

@@ -806,7 +806,6 @@ OS_OBJS +=	$(OBJDIR)/erl_mseg.o \
 		$(OBJDIR)/erl_$(ERLANG_OSTYPE)_sys_ddll.o \
 		$(OBJDIR)/erl_mtrace_sys_wrap.o
 
-HIPE_x86_darwin_OBJS=$(OBJDIR)/mach_override.o
 HIPE_x86_OS_OBJS=$(HIPE_x86_$(OPSYS)_OBJS)
 HIPE_x86_OBJS=$(OBJDIR)/hipe_x86.o $(OBJDIR)/hipe_x86_glue.o $(OBJDIR)/hipe_x86_bifs.o $(OBJDIR)/hipe_x86_signal.o $(OBJDIR)/hipe_x86_stack.o $(HIPE_x86_OS_OBJS)
 HIPE_amd64_OBJS=$(OBJDIR)/hipe_amd64.o $(OBJDIR)/hipe_amd64_glue.o $(OBJDIR)/hipe_amd64_bifs.o $(OBJDIR)/hipe_x86_signal.o $(OBJDIR)/hipe_x86_stack.o

erts/emulator/hipe/hipe_x86_signal.c

@@ -147,24 +147,30 @@ static void do_init(void)
 
 #if defined(__DARWIN__)
 /*
- * Darwin appears to require code patching in order to catch
- * and redirect calls to library functions. That functionality
- * is implemented by the mach_override library.
+ * Assumes Mac OS X >= 10.3 (dlsym operations not available in 10.2 and
+ * earlier).
+ *
+ * The code below assumes that is is part of the main image (earlier
+ * in the load order than libSystem and certainly before any dylib
+ * that might use sigaction) -- a standard RTLD_NEXT caveat.
+ *
+ * _sigaction lives in /usr/lib/libSystem.B.dylib and can be found
+ * with the standard dlsym(RTLD_NEXT) call. The proviso on Mac OS X
+ * being that the symbol for dlsym doesn't include a leading '_'.
+ *
+ * The other _sigaction, _sigaction_no_bind I don't understand the purpose
+ * of and don't modify.
  */
-#include "mach_override.h"
-static int my_sigaction(int signum, const struct sigaction *act, struct sigaction *oldact);
+#include <dlfcn.h>
 static int (*__next_sigaction)(int, const struct sigaction*, struct sigaction*);
 #define init_done()	(__next_sigaction != 0)
+#define __SIGACTION _sigaction
 static void do_init(void)
 {
-    kern_return_t err;
-
-    err = mach_override_ptr((void*)sigaction,
-			    (void*)my_sigaction,
-			    (void**)&__next_sigaction);
-    if (!err)
+    __next_sigaction = dlsym(RTLD_NEXT, "sigaction");
+    if (__next_sigaction != 0)
 	return;
-    perror("mach_override");
+    perror("dlsym_darwin");
     abort();
 }
 #define _NSIG NSIG