[PATCH] Switch vec_init and vec_extract optabs to 2 mode optab to allow extraction of vector from vector or initialization of vector from smaller vectors (PR target/80846)

[Eric Botcazou]

> Bootstrapped/regtested on x86_64-linux and i686-linux, where it improves
> e.g. the code generation for slp-43.c and slp-45.c testcases.
> make cc1 tested in cross-compilers to the remaining targets.

The SPARC bits are OK by me.

-- 
Eric Botcazou