make lsof configure with target includes, thanks to marcg

package/lsof/lsof.mk

@@ -10,6 +10,7 @@ LSOF_CAT:=$(BZCAT)
 LSOF_DIR:=$(BUILD_DIR)/lsof_$(LSOF_VERSION)
 LSOF_BINARY:=lsof
 LSOF_TARGET_BINARY:=bin/lsof
+LSOF_INCLUDE:=$(STAGING_DIR)/usr/include
 
 BR2_LSOF_CFLAGS:=
 ifeq ($(BR2_LARGEFILE),)
@@ -33,7 +34,7 @@ $(LSOF_DIR)/.unpacked: $(DL_DIR)/$(LSOF_SOURCE)
 	touch $(LSOF_DIR)/.unpacked
 
 $(LSOF_DIR)/.configured: $(LSOF_DIR)/.unpacked
-	(cd $(LSOF_DIR)/lsof_$(LSOF_VERSION)_src; echo n | $(TARGET_CONFIGURE_OPTS) DEBUG="$(TARGET_CFLAGS) $(BR2_LSOF_CFLAGS)" ./Configure linux)
+	(cd $(LSOF_DIR)/lsof_$(LSOF_VERSION)_src; echo n | $(TARGET_CONFIGURE_OPTS) DEBUG="$(TARGET_CFLAGS) $(BR2_LSOF_CFLAGS)" LSOF_INCLUDE="$(LSOF_INCLUDE)" ./Configure linux)
 	touch $(LSOF_DIR)/.configured
 
 $(LSOF_DIR)/lsof_$(LSOF_VERSION)_src/$(LSOF_BINARY): $(LSOF_DIR)/.configured