[Bug libstdc++/79017] Old PowerMac G5, MacPorts GCC 5.4, C++11 and "std::log2 has not been declared"

["noloader at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79017

--- Comment #5 from Jeffrey Walton <noloader at gmail dot com> ---
(In reply to Jonathan Wakely from comment #2)
> (In reply to Jeffrey Walton from comment #0)
> ...                       ^
> 
> Because these six functions are missing we treat all C99 math functions as
> missing. We could split the checks into two pieces, so we check for these
> separately, which would allow the rest of the C99 math library to be
> imported into namespace std.
> 
> But OS X 10.5.8 is pretty old, and this might not be worth doing if it
> doesn't affect current versions of OS x.

The issue seems to affect Android as well: http://stackoverflow.com/q/22922961.
I am not sure if its the exact same issue however.

Splitting the checks may benefit more than an ancient PowerMac.

For what its worth, I keep the antique hardware around for testing on the
PowerPC, which is big-endian. Otherwise it would be retired.