Enhance objdump's --disassemble switch so that it can now take an optional parameter...

Enhance objdump's --disassemble switch so that it can now take an optional parameter, specifying the starting symbol for disassembly.  Disassembly will continue from this symbol up to the next symbol.

	* objdump.c (long_options): Have the --disassemble option take an
	optional argument.
	(usage): Add description for the `symbol' argument to the
	--disassemble option.
	(disasm_sym): New file private variable.
	(struct objdump_disasm_info): New field `symbol'.
	(disassemble_section): Introduce `do_print' local variable
	to control whether objdump displays the result of disassembling
	for a symbol or not.
	(main): Set `symbol' file private variable if the option argument
	for the --disassemble option is given.
	* doc/binutils.texi (objdump): Add description for the option
	argument.
	* NEWS: Mention the new feature.
	* testsuite/binutils-all/objdump.exp: Add tests of the -d and
	--disassemble=<symbol> options.
	* testsuite/binutils-all/bintest.s: Add more symbols and code.
	* testsuite/binutils-all/readelf.s: Update expected output.
	* testsuite/binutils-all/readelf.ss-64: Likewise.
	* testsuite/binutils-all/readelf.ss-mips: Likewise.
	* testsuite/binutils-all/readelf.ss-tmips: Likewise.