Fixes https://github.com/llvm/llvm-project/issues/96197.
A global alias should always point to a definition. Ifuncs are
definitions, so far so good. However an ifunc may be statically resolved
to a function that is declared but not defined in the translation unit.
With this patch we perform static resolution if:
* the resolvee is defined, else if
* none of the ifunc users is a global alias
7c946f04cf