merge revision(s) 52124: [Backport #11591]

	* configure.in: check for libunwind.h, which is not available in
	  very old OS X SDK.  [ruby-core:71080] [Bug #11591]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@52354 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/vm_dump.c b/vm_dump.c
index 6caea9f5a5..d3cbf88ea8 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -435,7 +435,7 @@ rb_vmdebug_thread_dump_state(VALUE self)
 # if HAVE_LIBUNWIND
 #  undef backtrace
 #  define backtrace unw_backtrace
-# elif defined(__APPLE__) && defined(__x86_64__)
+# elif defined(__APPLE__) && defined(__x86_64__) && defined(HAVE_LIBUNWIND_H)
 #  define UNW_LOCAL_ONLY
 #  include <libunwind.h>
 #  undef backtrace