Fix console hang on unknown key press

* console-client/xkb/kstoucs.c (find_ucs): Remove middle value from
recursive call range.
Merge branch 'master' of git.savannah.gnu.org:/srv/git/hurd/hurd
SYMLOOP_MAX may be undefined under some build flags

* libdiskfs/boot-start.c (diskfs_start_bootstrap): Use value returned by
sysconf (_SC_SYMLOOP_MAX) instead of SYMLOOP_MAX.
utils/vmstat: Use gnumach.defs from gnumach

The gnumach installation provides the include file mach/gnumach.defs
instead of mach/gnumach.h.  This runs the defs file through MIG and
builds the result for vmstat.

* utils/vmstat.c: Replace <mach/gnumach.h> with "gnumach_U.h".
* utils/Makefile (vmstat): Add rule to depend on gnumach_U.o.
* Makeconf (mach_defs_names): Add gnumach.
Edited the readme file to better illustrate the context of this repo.