Add libunwind patch from Pyston

Author: tkelman

deps/0001-Change-the-RBP-validation-heuristic-to-allow-size-0-.patch

@@ -0,0 +1,22 @@
+From e1d7c78d95e4b73a311f10149d0a54547d307d5d Mon Sep 17 00:00:00 2001
+From: Kevin Modzelewski <[email protected]>
+Date: Tue, 22 Apr 2014 15:50:40 -0700
+Subject: [PATCH] Change the RBP-validation heuristic to allow size-0 call frames
+
+---
+diff --git a/src/x86_64/Gstep.c b/src/x86_64/Gstep.c
+index 9fa0967..809d60b 100644
+--- a/src/x86_64/Gstep.c
++++ b/src/x86_64/Gstep.c
+@@ -173,7 +173,7 @@ unw_step (unw_cursor_t *cursor)
+ 		 anything about new RBP (rbp1) since it may not be a frame
+ 		 pointer in the frame above.  Just check we get the value. */
+               if (ret < 0
+-		  || rbp <= c->dwarf.cfa
++		  || rbp < c->dwarf.cfa
+ 		  || (rbp - c->dwarf.cfa) > 0x4000)
+ 	        {
+                   rip_loc = DWARF_NULL_LOC;
+-- 
+1.7.4.1
+

deps/Makefile

@@ -1303,6 +1303,7 @@ libunwind-$(UNWIND_VER).tar.gz:
 	$(JLDOWNLOAD) $@ http://download.savannah.gnu.org/releases/libunwind/$@ 
 libunwind-$(UNWIND_VER)/configure: libunwind-$(UNWIND_VER).tar.gz
 	$(TAR) xfz $<
+	cd libunwind-$(UNWIND_VER) && patch -p1 < ../0001-Change-the-RBP-validation-heuristic-to-allow-size-0-.patch
 	touch -c $@
 libunwind-$(UNWIND_VER)/config.status: libunwind-$(UNWIND_VER)/configure
 	cd libunwind-$(UNWIND_VER) && \