spdlog update broke aff4

[chrstphrchvz (Christopher Chavez)]

It was observed in 2018 that updating spdlog to ≥ 1.0 would break aff4 (see [85b10ef0f8/macports-ports] and ​https://github.com/Velocidex/c-aff4/issues/38). This knowledge never made it to a comment in the spdlog portfile or a ticket where it would be easily noticed when someone tried updating it. spdlog has since been updated from 0.16.3 to 1.4.2 ([bb7d7b7b6d/macports-ports]) and then 1.5.0 ([7caf3d34e5/macports-ports]), and as expected aff4 ​currently fails to build:

libaff4.cc:536:24: error: no member named 'stderr_color_mt' in namespace 'spdlog'
        return spdlog::stderr_color_mt("aff4");
               ~~~~~~~~^
1 error generated.

[ryandesign (Ryan Carsten Schmidt)]

In 05ab953b1a432450aa9d00805b08db9ded4902ee/macports-ports (master):

aff4: Build using spdlog0

Closes: #61127

Also use compiler.cxx_standard instead of cxx11 1.1 portgroup.

[ghosthound]

All good, and thanks for the creating/reopening the c-aff4 ticket (​https://github.com/Velocidex/c-aff4/issues/38) as well.