docs: unbreak spec build

[exim.git] / src / OS / Makefile-Linux

diff --git a/src/OS/Makefile-Linux b/src/OS/Makefile-Linux
index 4fe2436a69885a335296e9991b585be23952f180..990f884e9cb2b33ac3ce734986c461312b21449e 100644 (file)
--- a/src/OS/Makefile-Linux
+++ b/src/OS/Makefile-Linux
@@ -1,7 +1,9 @@
-# $Cambridge: exim/src/OS/Makefile-Linux,v 1.4 2008/08/11 15:30:02 fanf2 Exp $
-
 # Exim: OS-specific make file for Linux. This is for modern Linuxes,
 # which use libc6.
+#
+# For Linux, we assume GNU Make; at time of writing, the only extension
+# used is ?= which is actually portable to other maintained Make variants,
+# just is not POSIX.
 
 HAVE_ICONV=yes
 
@@ -10,8 +12,9 @@ CHOWN_COMMAND=look_for_it
 CHGRP_COMMAND=look_for_it
 CHMOD_COMMAND=look_for_it
 
-CFLAGS=-O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-CFLAGS_DYNAMIC=-shared -rdynamic
+# Preserve CFLAGS and CFLAGS_DYNAMIC from the caller/environment
+CFLAGS ?= -O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+CFLAGS_DYNAMIC ?= -shared -rdynamic
 
 DBMLIB = -ldb
 USE_DB = yes