macOS Catalina: FAIL: t-powm

[Hans Åberg]

> On 16 Nov 2019, at 14:21, Jack Howarth <howarth.mailing.lists at gmail.com> wrote:
> 
> The gmp package in MacPorts relies on always building with the core2 architecture in order ship uniform packaging of gmp for all Intel based Macs. That is why everyone sees the same glitch in Xcode 11 who is using MacPorts.

The make check passed with clang when turning off optimization, but it seems not known how much performance loss, if any, that results. Also, one might check if the tests fail when turning off optimization only when compiling the library or the test.