Makefile: Use ?= so variables can be set on command line.

1 files changed, 5 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index 55b6645..6abaa97 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,9 @@
-CFLAGS=-g -O3 -Wall -Wextra -std=c99 -Isrc $(OPTFLAGS)
-LDFLAGS=-g -O3 -Wall -Werror
-SRCDIR=src
-DATADIR=data
+CFLAGS?=-g -O3 -Wall -Wextra -std=c99 -Isrc $(OPTFLAGS)
+LDFLAGS?=-g -O3 -Wall -Werror
+SRCDIR?=src
+DATADIR?=data
 
-PROG=./stmd
+PROG?=./stmd
 
 .PHONY: all oldtests test spec benchjs testjs
 all: $(SRCDIR)/case_fold_switch.c $(PROG)