add conditional variable assignment operator to CHROOT_DIR
diff --git a/gotweb/Makefile.inc b/gotweb/Makefile.inc
index f7c4df6..445d054 100644
--- a/gotweb/Makefile.inc
+++ b/gotweb/Makefile.inc
@@ -1,7 +1,7 @@
KCGIBASE ?= /usr/local
LDADD += -lz -lutil
LDSTATIC = ${STATIC}
-CHROOT_DIR = /var/www
+CHROOT_DIR ?= /var/www
GOTWEB_DIR = /cgi-bin/gotweb
LIBEXECDIR = ${GOTWEB_DIR}/libexec
LIBEXEC_DIR = ${CHROOT_DIR}${LIBEXECDIR}