build: Make XEN_ROOT an absolute path.

Otherwise make can search the path relative to certain standard paths
such as /usr/include (e.g., the line '-include $(XEN_ROOT)/.config' in
Config.mk suffers from this).

Signed-off-by: Keir Fraser <keir@xen.org>

xen-unstable changeset: 23049:ff3b7749008b
Backport-requested-by: Allen M Kay <allen.m.kay@intel.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/debugger/gdbsx/Makefile

@@ -1,4 +1,4 @@
-XEN_ROOT = ../../..
+XEN_ROOT = $(CURDIR)/../../..
 include ./Rules.mk
 
 .PHONY: all

tools/debugger/gdbsx/gx/Makefile

@@ -1,4 +1,4 @@
-XEN_ROOT = ../../../..
+XEN_ROOT = $(CURDIR)/../../../..
 include ../Rules.mk
 
 GX_OBJS := gx_comm.o gx_main.o gx_utils.o gx_local.o

tools/debugger/gdbsx/xg/Makefile

@@ -1,4 +1,4 @@
-XEN_ROOT = ../../../..
+XEN_ROOT = $(CURDIR)/../../../..
 include ../Rules.mk
 
 XG_HDRS := xg_public.h 

tools/debugger/kdd/Makefile

@@ -1,4 +1,4 @@
-XEN_ROOT = ../../..
+XEN_ROOT = $(CURDIR)/../../..
 include $(XEN_ROOT)/tools/Rules.mk
 
 CFLAGS  += $(CFLAGS_libxenctrl)

tools/debugger/xenitp/Makefile

@@ -1,4 +1,4 @@
-XEN_ROOT=../../..
+XEN_ROOT=$(CURDIR)/../../..
 include $(XEN_ROOT)/tools/Rules.mk
 
 #CFLAGS  += -Werror -g -O0