diagnostics: keep the fixits

Introduce proper support for fixits, instead of just printing them on
demand.

* bootstrap.conf: We need gnulib's xlists.
* src/fixits.h, src/fixits.c: New.
* src/complain.c (deprecated_directive): Use fixits_register.
* src/main.c (main): Use fixits_free.

lib/.gitignore

@@ -8,6 +8,10 @@
 /alignof.h
 /alloca.h
 /alloca.in.h
+/allocator.c
+/allocator.h
+/areadlink.c
+/areadlink.h
 /arg-nonnull.h
 /argmatch.c
 /argmatch.h
@@ -18,6 +22,11 @@
 /binary-io.h
 /bitrotate.c
 /bitrotate.h
+/bitset.c
+/bitset.h
+/bitset/
+/bitsetv.c
+/bitsetv.h
 /c++defs.h
 /c-ctype.c
 /c-ctype.h
@@ -26,6 +35,9 @@
 /c-strcaseeq.h
 /c-strncasecmp.c
 /calloc.c
+/canonicalize-lgpl.c
+/careadlinkat.c
+/careadlinkat.h
 /charset.alias
 /cloexec.c
 /cloexec.h
@@ -78,6 +90,8 @@
 /fseterr.h
 /fstat.c
 /getdtablesize.c
+/gethrxtime.c
+/gethrxtime.h
 /getopt-cdefs.in.h
 /getopt-core.h
 /getopt-ext.h
@@ -90,7 +104,16 @@
 /getopt_int.h
 /getprogname.c
 /getprogname.h
+/getrusage.c
 /gettext.h
+/gettime.c
+/gettimeofday.c
+/gl_array_list.c
+/gl_array_list.h
+/gl_list.c
+/gl_list.h
+/gl_xlist.c
+/gl_xlist.h
 /gnulib.mk
 /hard-locale.c
 /hard-locale.h
@@ -112,6 +135,8 @@
 /limits.in.h
 /localcharset.c
 /localcharset.h
+/localtime-buffer.c
+/localtime-buffer.h
 /lstat.c
 /malloc.c
 /malloca.c
@@ -150,17 +175,23 @@
 /printf.c
 /progname.c
 /progname.h
+/progreloc.c
 /quote.h
 /quotearg.c
 /quotearg.h
 /raise.c
 /rawmemchr.c
 /rawmemchr.valgrind
+/readlink.c
 /realloc.c
 /ref-add.sed
 /ref-del.sed
+/relocatable.c
+/relocatable.h
+/relocwrapper.c
 /sched.h
 /sched.in.h
+/setenv.c
 /sig-handler.c
 /sig-handler.h
 /sigaction.c
@@ -190,6 +221,8 @@
 /spawnp.c
 /sprintf.c
 /stamp-h1
+/stat-time.c
+/stat-time.h
 /stat-w32.c
 /stat-w32.h
 /stat.c
@@ -223,13 +256,20 @@
 /strverscmp.c
 /sys
 /sys_ioctl.in.h
+/sys_resource.in.h
 /sys_socket.in.h
 /sys_stat.in.h
+/sys_time.in.h
+/sys_times.in.h
 /sys_types.in.h
 /sys_wait.in.h
 /sysexits.in.h
 /time.h
 /time.in.h
+/timespec.c
+/timespec.h
+/timevar.c
+/timevar.h
 /unistd--.h
 /unistd-safer.h
 /unistd.c
@@ -267,45 +307,11 @@
 /xmalloc.c
 /xmemdup0.c
 /xmemdup0.h
+/xreadlink.c
+/xreadlink.h
 /xsize.c
 /xsize.h
 /xstrndup.c
 /xstrndup.h
-/stat-time.c
-/stat-time.h
-/timevar.c
-/timevar.h
-/sys_time.in.h
-/sys_times.in.h
-/gethrxtime.c
-/gethrxtime.h
-/getrusage.c
-/gettime.c
-/gettimeofday.c
-/localtime-buffer.c
-/localtime-buffer.h
-/sys_resource.in.h
-/timespec.c
-/timespec.h
 /xtime.c
 /xtime.h
-/bitset.c
-/bitset.h
-/bitset/
-/bitsetv.c
-/bitsetv.h
-/allocator.c
-/allocator.h
-/areadlink.c
-/areadlink.h
-/canonicalize-lgpl.c
-/careadlinkat.c
-/careadlinkat.h
-/progreloc.c
-/readlink.c
-/relocatable.c
-/relocatable.h
-/relocwrapper.c
-/setenv.c
-/xreadlink.c
-/xreadlink.h