PATCH RFC: Recognize gold in libstdc++ configure script

[Joe Buck]

I wrote:
> It depends.  If the test is for gold because gold is missing a feature,
> another change is needed when the feature is eventually added to gold (in
> this case, --gc-sections).  I assume that at some point you (Ian) or
> someone will add it, right?

Sorry, ignore this; I see that Ian's patch checks the help output
for --gc-sections to detect a later addition.