Collapsed ensure_state_size and ensure_all_state_sizes into one
function named resize_all_states. Allocate new vectors outside of
single threaded region. Do only simple things inside that region.
(scm_make_fluid, scm_make_dynamic_state): Lock fluid_admin_mutex while
adding to the global lists.
(scm_i_thread): Removed unused signal_asyncs field.
(threads_mark): Do not mark it.
(guilify_self_1): Do not initialize it. Do initialize
continuation_root field.
(do_thread_exit): Do not remove thread from all_threads list.
(on_thread_exit): Do it here, after leaving guile mode.
(sleep_level): Removed.
(scm_i_thread_put_to_sleep): Leave thread_admin_mutex locked when
returning. Do not support recursive sleeps.
(scm_i_thread_wake_up): Expect thread_admin_mutex to be locked on
entry. Do not support recursive sleeps.
AC_CHECK_LIB instead. Do not subst LTDLINCL and LIBLTDL. Do not
add "-DLIBLTDL_DLL_IMPORT" on MINGW32.
* Makefile.am (SUBDIRS): Removed libltdl.
* README: Talk about required external packages.
* autogen.sh: Do not call libtoolize.
SCM_CRITICAL_SECTION_END): Moved here from threads.h since now
they also block/unblock execution of asyncs and call
scm_async_click which is declared in async.h but threads.h can not
include async.h since async.h already includes threads.h.
(scm_i_critical_section_level): New, for checking mistakes in the
use of the SCM_CRITICAL_SECTION_* macros.
(scm_i_critical_section_mutex): Make it a recursive mutex so that
critical sections can be nested.
* threads.h, threads.c (scm_frame_lock_mutex): New.
(scm_frame_critical_section): Take mutex as argument.
(framed_critical_section_mutex): New, used as default for above.
(scm_init_threads): Initialize it.
(scm_threads_prehistory): Do not initialize thread_admin_mutex and
scm_i_critical_section_mutex; both are initialized statically.
