libgccjit: depend on gcc

[fxcoudert]

See https://github.com/orgs/Homebrew/discussions/5364

[Bo98]

Do we need the dependency on Linux?

[carlocab]

#171811

[fxcoudert]

To be honest, I don't understand how this happens to work with a non-GCC compiler (or a different version of the GCC compiler). libgccjit is a giant wrapping of the GCC compiler itself, and it emits GCC-generated code, so it will call functions from its runtime library.

Ah, found it:

Breakpoint 2: where = libcompiler_rt.dylib`__muldc3, address = 0x000000018d09a1b8

so it is using the clang runtime libraries from the system. Doesn't seem like a good thing, though. And not sure that all functions are provided.

[Bo98]

Linux question was more of a question whether we need the latest GCC or whether using the system GCC (Homebrew's minimum is 11) is OK.