The purpose of this patch is to make guile's internal memoizers

	The purpose of this patch is to make guile's internal memoizers
	distinguishable from memoizing macros created on the scheme level
	or from user provided primitive memoizing macros.  The reason is,
	that the internal memoizers are the only ones that are allowed to
	transform their scheme input into memoizer byte code, while all
	other memoizing macros may only transform scheme code into new
	scheme code.

	To achieve this, a new macro type 'builtin-macro!' is introduced.
	Currently, 'builtin-macro!'s are handled as memoizing macros, but
	this will change when the memoizer and executor are separated.

	* macros.[ch] (scm_i_makbimacro): New.

	* macros.h (SCM_BUILTIN_MACRO_P): New.

	* macros.c (macro_print, scm_macro_type): Support builtin-macro!s.

	* eval.c, goops.c: All of guile's primitive memoizing macros are
	primitive builtin-macros now.

	* eval.c (scm_macroexp, SCM_CEVAL): Make sure the primitive
	builtin-macros are handled equally to memoizing macros.