* gdbint.texinfo: General round of cleanup and minor

	* gdbint.texinfo: General round of cleanup and minor
	clarifications.
	(Breakpoint Handling): Remove mention of BREAKPOINT macro.
	(Longjmp Support): Update description to reflect how it is done
	for targets without using native header.
	(Symbol Handling): Add a little more general explanation.
	(COFF, ELF): Mention stabs encapsulation.
	(DWARF 3): New section.
	(Adding a New Host): Scrub out some obsolete bits.
	(Generic Host Support Files): Mention ser-pipe.c, ser-mingw.c.
	(Host Conditionals): Remove descriptions of NO_STD_REGS,
	HAVE_MMAP, HAVE_TERMIO, INT_MAX etc, LONGEST, HAVE_LONG_DOUBLE,
	PRINTF_HAS_LONG_DOUBLE, SCANF_HAS_LONG_DOUBLE, L_SET, SEEK_CUR,
	SEEK_SET, STOP_SIGNAL, USG.
	(Raw and Virtual Register Representations): Ditto for
	DEPRECATED_REGISTER_RAW_SIZE, DEPRECATED_REGISTER_VIRTUAL_SIZE,
	DEPRECATED_REGISTER_VIRTUAL_TYPE, REGISTER_CONVERT_TO_TYPE.
	(Target Conditionals): Ditto for DEPRECATED_FP_REGNUM,
	DEPRECATED_FRAMELESS_FUNCTION_INVOCATION, DEPRECATED_FRAME_CHAIN,
	DEPRECATED_FRAME_CHAIN_VALID, DEPRECATED_FRAME_INIT_SAVED_REGS,
	DEPRECATED_FRAME_SAVED_PC, DEPRECATED_FUNCTION_START_OFFSET,
	DEPRECATED_REGISTER_VIRTUAL_SIZE,
	DEPRECATED_REGISTER_VIRTUAL_TYPE,
	DEPRECATED_USE_STRUCT_CONVENTION.
	Describe gdbarch_deprecated_fp_regnum.
	Update description of gdbarch_print_insn.
	(Adding a New Target): Scrub out obsolete bits.
	(Obsolete Conditionals): Remove entire section.