From 45bb97cad60bd4430fa1c98b6e20d56eb477ec32 Mon Sep 17 00:00:00 2001
From: Michael Vines <mvines@gmail.com>
Date: Tue, 30 Oct 2018 07:58:09 -0700
Subject: [PATCH] Permit {INC,LLVM,OUT,SRC,SYSTEM_INC}_DIRs to be overridden

---
 programs/bpf/c/sdk/bpf.mk | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/programs/bpf/c/sdk/bpf.mk b/programs/bpf/c/sdk/bpf.mk
index 01ccbd50ed..87dc1bcf96 100644
--- a/programs/bpf/c/sdk/bpf.mk
+++ b/programs/bpf/c/sdk/bpf.mk
@@ -6,16 +6,16 @@ ifneq ($(V),1)
 _@ :=@
 endif
 
-INC_DIRS :=
-SYSTEM_INC_DIRS := -isystem $(dir $(lastword $(MAKEFILE_LIST)))inc
-SRC_DIR := ./src
-OUT_DIR := ./out
+SYSTEM_INC_DIRS ?= -isystem $(dir $(lastword $(MAKEFILE_LIST)))inc
+INC_DIRS ?=
+SRC_DIR ?= ./src
+OUT_DIR ?= ./out
 
 OS=$(uname)
 ifeq ($(OS),Darwin)
-LLVM_DIR := $(brew --prefix llvm)
+LLVM_DIR ?= $(brew --prefix llvm)
 else
-LLVM_DIR := /usr/local/opt/llvm
+LLVM_DIR ?= /usr/local/opt/llvm
 endif
 
 CC := $(LLVM_DIR)/bin/clang