Name fixup is undone by replace_illegal_names in the case of entry points

[VZout]

Currently fixup_reserved_names fixes names to not include invalid characters. However this fixup is undone later by replace_illegal_names.

See the offending line: https://github.com/KhronosGroup/SPIRV-Cross/blob/master/spirv_msl.cpp#L12189

This has the side effect of also breaking structs with invalid names if a entry points returns that struct.

Possible solution is calling fixup_reserved_names (https://github.com/KhronosGroup/SPIRV-Cross/blob/master/spirv_msl.cpp#L1183) after replace_illegal_names (https://github.com/KhronosGroup/SPIRV-Cross/blob/master/spirv_msl.cpp#L1231)

Another possible solution is writing

if (illegal_func_names.find(ep_name) != end(illegal_func_names))
{
	ep_name += "0";
	ir.meta[entry.first].decoration.alias += "0";
}

instead of

string &ep_name = entry.second.name;
if (illegal_func_names.find(ep_name) != end(illegal_func_names))
{
	ep_name += "0";
	ir.meta[entry.first].decoration.alias += "0";
}

// Always write this because entry point might have been renamed earlier.
ir.meta[entry.first].decoration.alias = ep_name;

What do y'all think? This is currently a major issue for https://github.com/EmbarkStudios/rust-gpu