[SPIR-V] Invalid handling of vk::ext_decorate with Location, BuiltIn decorations

[Keenuts]

Inline SPIR-V provides multiple ways to declare a builtin input:

the shortcut: vk::ext_builtin_input
the tedious way: vk::ext_decorate + vk::ext_storage_class

Issue is DXC is not considering the user going through the tedious way, but the shortcut should in fact be seen as a shortcut, not the only valid solution.