build-sys: introduce $sysconfstaticdir

The current situation is that distros differentiate between:

* host specific configuration -- usually /etc, maintained by admin

* distribution specific (static) configuration -- usually /usr/lib,
  maintained by ditro packages

Unfortunately autotools have clue about $sysconfdir (/etc) only. This
patch introduces $sysconfstaticdir (default $prefix/lib).

Signed-off-by: Karel Zak <kzak@redhat.com>

Makefile.am

@@ -2,7 +2,9 @@ AM_CPPFLAGS = \
 	-include config.h \
 	-I$(top_srcdir)/include \
 	-DLOCALEDIR=\"$(localedir)\" \
-	-D_PATH_RUNSTATEDIR=\"${runstatedir}\"
+	-D_PATH_RUNSTATEDIR=\"${runstatedir}\" \
+	-D_PATH_SYSCONFSTATICDIR=\"${sysconfstaticdir}\"
+
 AM_CFLAGS = -fsigned-char $(WARN_CFLAGS)
 AM_LDFLAGS = $(ASAN_LDFLAGS)
 

configure.ac

@@ -101,6 +101,14 @@ AS_CASE([$libdir],
 )
 AC_SUBST([usrlib_execdir])
 
+# static configuration maintaned by packages (e.g. /usr/lib)
+AC_ARG_VAR([SYSCONFSTATICDIR],
+	   [Path to static system configuration, default ${prefix}/lib])
+AS_IF([test "x$SYSCONFSTATICDIR" = x],
+      [sysconfstaticdir='${prefix}/lib'],
+      [sysconfstaticdir=$SYSCONFSTATICDIR])
+AC_SUBST([sysconfstaticdir])
+
 
 AM_PROG_CC_C_O
 AC_PROG_MKDIR_P