Fix Trac ticket:46.

Make the size of all spaces configurable from the command line.

code/commandline.lisp:
o Define the switches so lisp doesn't complain.

general-info/lisp.1:
o Document new switches.

general-info/release-20c.txt:
o Update

lisp/Darwin-os.c
lisp/FreeBSD-os.c
lisp/Linux-os.c
lisp/NetBSD-os.c
lisp/backtrace.c
lisp/cgc.c
lisp/gencgc.c
lisp/os-common.c
lisp/ppc-validate.h
lisp/purify.c
lisp/solaris-os.c
lisp/sparc-arch.c
lisp/sparc-validate.h
lisp/x86-validate.h:
lisp/validate.c
o Basically rename CONTROL_STACK_SIZE, BINDING_STACK_SIZE,
  READ_ONLY_SPACE_SIZE, and STATIC_SPACE_SIZE to control_stack_size,
  binding_stack_size, read_only_space_size, and static_space_size,
  respectively.

lisp/coreparse.c
o Check the space size in the core file against the allocated size.
  If the allocated space is too small, print an error message and
  exit.

lisp/globals.c
o Define new variables for the allocated size of spaces.

lisp/globals.h
o Declare the new variables for the size of the spaces.

lisp/lisp.c
o Set the default values of the spaces.
o Parse the new command-line flags and set the space sizes.

lisp/sunos-os.c:
o Added os_init0 (that we forgot last time).

lisp/x86-assem.S:
o Change $CONTROL_STACK_END to GNAME(control_stack_end) to get the
  correct end of the stack.