build: add configure-time --enable-gcc-warnings option; avoid warnings

* bootstrap.conf (gnulib_modules): Add "warnings" module.
* configure.ac: Add --enable-gcc-warnings, derived from code in bison.
* src/Makefile.am (AM_CFLAGS): Set to $(WARN_CFLAGS) # $(WERROR_CFLAGS)
* lib/Makefile.am (AM_CFLAGS): Change spelling to $(WARN_CFLAGS)
Don't use $(WERROR_CFLAGS), yet.
* src/system.h (usage): Declare.
* src/base64.c (usage): Declare to be global, for consistency.
* src/timeout.c (usage): Likewise.
* src/truncate.c (usage): Likewise.
* src/getlimits.c (usage): Likewise.
* src/pinky.c (ttyname): Declare with prototype, rather than an
empty argument list.
* src/who.c (ttyname): Likewise.
* src/su.c (crypt, getusershell, setusershell, endusershell): Likewise.

diff --git a/src/Makefile.am b/src/Makefile.am
index 819b87461a8d399f8519a95be5a6b707c0996503..68c5f75f650dbb42f9e1ea3bd139d5959e5b46e4 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -26,7 +26,7 @@ no_install__progs = \
 build_if_possible__progs = \
   chroot df hostid nice pinky stty su uname uptime users who
 
-AM_CFLAGS = $(WARN_CFLAGS) $(WERROR_CFLAGS)
+AM_CFLAGS = $(WARN_CFLAGS) # $(WERROR_CFLAGS)
 
 EXTRA_PROGRAMS = \
   $(no_install__progs) \