Make it possible to use gcc:var/setup without hardening wrapper

In projects/gcc/config we define var/setup which can be used in the build scripts from other components to setup gcc. It is however assuming we want to use hardening-wrapper, which prevents us from using it in projects/firefox/build to setup a gcc host compiler in the Windows build.

It also seems we want to use gcc to build llvm (as part of the changes for #26073 (moved)), without hardening-wrapper: https://github.com/arthuredelstein/tor-browser-build/commit/80c6edec3de1b3a2a1d8f879c95b0bf804cdf9f0