build: document WERROR_CFLAGS

* README-hacking: Mention 'make WERROR_CFLAGS='.

diff --git a/README-hacking b/README-hacking
index 4f6de6529a500b8d2db514c11d47ed4b19e72438..0381d513c496f1dac11e9a6c444da3af1f8a0d91 100644 (file)
--- a/README-hacking
+++ b/README-hacking
@@ -14,6 +14,10 @@ version.
 - Texinfo <http://www.gnu.org/software/texinfo>
 - Git <http://git.or.cz>
 
+Up-to-date compilers and libraries are also recommended, for better
+static checking.  You may be able to use an older compiler by building
+with 'make WERROR_CFLAGS='; if so, don't worry about its false alarms.
+
 * Bootstrapping
 
 Obviously, if you are reading these notes, you did manage to clone