build: include Tools.mk first in tools/Rules.mk

Tools.mk should be included first, or PREFIX is not honoured in the
other conf/ files that define the paths of several tools.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

tools/Rules.mk

@@ -3,8 +3,8 @@
 # `all' is the default target
 all:
 
-include $(XEN_ROOT)/Config.mk
 -include $(XEN_ROOT)/config/Tools.mk
+include $(XEN_ROOT)/Config.mk
 
 export _INSTALL := $(INSTALL)
 INSTALL = $(XEN_ROOT)/tools/cross-install