Implement flags to expose calling conventions, storage classes, ptr64, etc

[mstange]

We may want to support all flags from https://msdn.microsoft.com/en-us/library/ms681400(VS.85).aspx .

[mstange]

I've added some of these:

msvc-demangler-rust/src/lib.rs

Lines 80 to 122 in 4361884

	pub struct DemangleFlags: u32 {
	/// Undecorate 32-bit decorated names.
	const DECODE_32_BIT = 0x0800;
	/// Enable full undecoration.
	const COMPLETE = 0x0000;
	/// Undecorate only the name for primary declaration. Returns [scope::]name. Does expand template parameters.
	const NAME_ONLY = 0x1000;
	/// Disable expansion of access specifiers for members.
	const NO_ACCESS_SPECIFIERS = 0x0080;
	// /// Disable expansion of the declaration language specifier.
	// const NO_ALLOCATION_LANGUAGE = 0x0010;
	// /// Disable expansion of the declaration model.
	// const NO_ALLOCATION_MODEL = 0x0008;
	// /// Do not undecorate function arguments.
	// const NO_ARGUMENTS = 0x2000;
	/// Disable expansion of CodeView modifiers on the this type for primary declaration.
	const NO_CV_THISTYPE = 0x0040;
	/// Disable expansion of return types for primary declarations.
	const NO_FUNCTION_RETURNS = 0x0004;
	// /// Remove leading underscores from Microsoft keywords.
	// const NO_LEADING_UNDERSCORES = 0x0001;
	/// Disable expansion of the static or virtual attribute of members.
	const NO_MEMBER_TYPE = 0x0200;
	/// Disable expansion of Microsoft keywords.
	const NO_MS_KEYWORDS = 0x0002;
	/// Disable expansion of Microsoft keywords on the this type for primary declaration.
	const NO_MS_THISTYPE = 0x0020;
	// /// Disable expansion of the Microsoft model for user-defined type returns.
	// const NO_RETURN_UDT_MODEL = 0x0400;
	// /// Do not undecorate special names, such as vtable, vcall, vector, metatype, and so on.
	// const NO_SPECIAL_SYMS = 0x4000;
	/// Disable all modifiers on the this type.
	const NO_THISTYPE = Self::NO_MS_THISTYPE.bits | Self::NO_CV_THISTYPE.bits;
	// /// Disable expansion of throw-signatures for functions and pointers to functions.
	// const NO_THROW_SIGNATURES = 0x0100;
	/// Disable output of struct/union/class/enum specifiers.
	// (Not sure if this duplicates an existing flag)
	const NO_CLASS_TYPE = 0x100000;
	/// Insert a space after each comma.
	const SPACE_AFTER_COMMA = 0x200000;
	/// Make * and & hug the type name.
	const HUG_TYPE = 0x400000;
	}

Not sure if they're all implemented correctly.

I also added a few flags that I made up myself: NO_CLASS_TYPE, SPACE_AFTER_COMMA and HUG_TYPE.