[clang][WebAssembly] Link crt1 even in case of -shared

This allows -mexec-model=reactor -shared produces a library module
with _initialize entrypoint, which is preferrable over __wasm_call_ctors.

This partially reverts https://reviews.llvm.org/D153293

Discussion: https://github.com/dicej/component-linking-demo/issues/3

Reviewed By: sbc100

Differential Revision: https://reviews.llvm.org/D156205