build: criu -- Drop host vars

They are already defined and exported.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/Makefile

-#
-# HOST part is needed to build helper
-# tools such as piegen.
-HOSTCC			?= gcc
-HOSTLD			?= ld
-HOSTCFLAGS		?= $(CFLAGS)
-CFLAGS			+= $(USERCFLAGS)
-
 # here is a workaround for a bug in libnl-3:
 # 6a8d90f5fec4 "attr: Allow attribute type 0" 
 WRAPFLAGS		+= -Wl,--wrap=nla_parse,--wrap=nlmsg_parse
 
-export HOSTCC HOSTLD HOSTCFLAGS
-
 ifeq ($(ARCH),x86)
         SRCARCH		:= x86
         LDARCH		:= i386:x86-64