[make] use sed -i in expandwaf rule (closes gh-401, thanks to @Jamin)

diff --git a/Makefile b/Makefile
index 97d9d19..51cfe4c 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -56,7 +56,8 @@ expandwaf: getwaf
        [ -d wafilb ] || rm -fr waflib
        $(WAFCMD) --help > /dev/null
        mv .waf*/waflib . && rm -fr .waf*
-       sed '/^#==>$$/,$$d' waf > waf2 && mv waf2 waf
+       sed -i.orig '/^#==>$$/,$$d' waf
+       rm -f waf.orig
        chmod +x waf && chmod -R go-w waflib
 
 cleanwaf: