[MC] Make symbol version errors non-fatal
We stil don't have a source location, which is pretty lame, but at
least we won't tell the user to file a clang bug report anymore.
Fixes PR40712
This will make errors for symbols with @@ versions that are not defined
non-fatal. For example:
void f(void)
{
__asm__(".symver foo,bar@@baz");
}
will now result in:
error: versioned symbol bar@@baz must be defined
instead of clang crashing with a diagnostic report.
PR: 234671
Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=40712
MFC after: 3 days
381ab04f4f