Devolve more validate macros

* libguile.h: Add chooks.h.
* libguile/Makefile.am: Add chooks.h and chooks.c.
* libguile/chooks.c:
* libguile/chooks.h: New files, for the C implementation of hooks.
  Broken out to avoid cycles in gc.h includes.
* libguile/gc.h:
* libguile/gc.c (scm_i_gc_admin_mutex, scm_i_sweep_mutex): Remove unused
  mutexes.  Include chooks instead of hooks in the main header.
* libguile/deprecated.h (scm_gc_running_p): Deprecate this macro always
  defined to 0.
  (SCM_VALIDATE_VECTOR_OR_DVECTOR): Deprecate this weird one too.
* libguile/array-map.c: Add procs.h include.
* libguile/threads.h:
* libguile/vm.c:
* libguile/r6rs-ports.c: Add smob.h include.
* libguile/atomic.h (SCM_VALIDATE_ATOMIC_BOX): Devolve.
* libguile/deprecation.c (scm_c_issue_deprecation_warning): Remove use
  of scm_gc_running_p.
* libguile/error.c (scm_error_scm): Remove use of scm_gc_running_p.
* libguile/filesys.h (SCM_VALIDATE_DIR)
* libguile/fluids.h (SCM_VALIDATE_FLUID)
* libguile/fports.h (SCM_VALIDATE_FPORT, SCM_VALIDATE_OPFPORT)
* libguile/generalized-arrays.h (SCM_VALIDATE_ARRAY)
* libguile/hooks.h (SCM_VALIDATE_HOOK)
* libguile/keywords.h (SCM_VALIDATE_KEYWORD)
* libguile/ports.h (SCM_VALIDATE_PORT, SCM_VALIDATE_INPUT_PORT)
  (SCM_VALIDATE_OUTPUT_PORT, SCM_VALIDATE_OPINPORT)
  (SCM_VALIDATE_OPENPORT, SCM_VALIDATE_OPPORT, SCM_VALIDATE_OPOUTPORT)
* libguile/procs.h (SCM_VALIDATE_PROC)
* libguile/random.h (SCM_VALIDATE_RSTATE)
* libguile/regex-posix.h (SCM_VALIDATE_RGXP)
* libguile/stacks.h (SCM_VALIDATE_STACK, SCM_VALIDATE_FRAME)
* libguile/strports.h (SCM_VALIDATE_OPOUTSTRPORT)
* libguile/struct.h (SCM_VALIDATE_STRUCT SCM_VALIDATE_VTABLE)
* libguile/symbols.h (SCM_VALIDATE_SYMBOL)
* libguile/variable.h (SCM_VALIDATE_VARIABLE)
* libguile/vectors.h (SCM_VALIDATE_VECTOR SCM_VALIDATE_VECTOR_LEN):
  Devolve.
* libguile/validate.h: It's empty now!

hooks squish

libguile/threads.h

@@ -31,6 +31,7 @@
 #include "libguile/throw.h"
 #include "libguile/dynstack.h"
 #include "libguile/iselect.h"
+#include "libguile/smob.h"
 #include "libguile/continuations.h"
 
 #if SCM_USE_PTHREAD_THREADS