[SPIR-V] DXC won't emit OpEntryPoint for library target profile

[alichraghi]

Description
DXC won't emit OpEntryPoint for library target profile

Steps to Reproduce
https://godbolt.org/z/9nzWqnqr6

Actual Behavior
Should emit OpEntryPoint for each entry-point specified with -E argument but instead throws this error:

fatal error: generated SPIR-V is invalid: No OpEntryPoint instruction was found. This is only allowed if the Linkage capability is being used.
note: please file a bug report on https://github.com/Microsoft/DirectXShaderCompiler/issues with source code if possible

Environment

• DXC version: goldbolt trunk
• Host Operating System: -

[alichraghi]

I forgot [shader("<stage>")] exist