math/glm: make it compile with GCC 7

[fernape]

Summary

GCC 7 was set as default in r475856.

cad/openvsp broke because it used some headers from math/glm but try to compile them with GCC. On the other side, math/glm doesn't recognize GCC 7.x as a valid compiler. Import changes from dd48b56e44d699a022c69155c8672caacafd9e8a to update the list of supported compilers.

Test Plan

For both math/glm and cad/openvsp:

• portlint -AC OK
• poudriere builds for {10.4,11.1}{amd64,i386}, 12i386 OK

No other ports depending on math/glm try to build with gcc as far as I can see.

[tcberner]

I think you need to bump the port revision. Otherwise the change won't be picked up, and the installed header would be still the unpatched one.

[fernape]

In D16650#353803, @tcberner wrote:

I think you need to bump the port revision. Otherwise the change won't be picked up, and the installed header would be still the unpatched one.

I'm not convinced that is strictly necessary. People building from ports will see the change when updating the tree and they'll be able to build cad/openvsp with the new math/glm (other ports are not affected by this). People using packages, will just install cad/openvsp 3.16.0 normally.

[fernape]

Bump PORTREVISION :)