Update objdump's --disassemble=<symbol> feature so that if <symbol> is a function...

Update objdump's --disassemble=<symbol> feature so that if <symbol> is a function, the entire function will be disassembled, regardless of the presence of interveening symbols.

	* objdump.c (disassemble_section): When disassembling from a
	symbol only stop at the next symbol if the original symbol was not
	a function symbol.  Otherwise continue disassembling until a new
	function is reached.
	* testsuite/binutils-all/objdump.exp: Add tests of extended
	functionality.
	* testsuite/binutils-all/disasm.s: New test source file.