Prefer cc/gcc over clang on Solaris

[shyouhei]

Requested by @tankf33der at https://bugs.ruby-lang.org/issues/17949#change-92430

[shyouhei]

Our CI is basically a no-op here, because we don't have a Solaris+clang combination. I need someone else's review before pressing the green merge button.

[tankf33der]

Testing, will be back asap.

[tankf33der]

Solaris11 compiles by gcc by this patch out of box.

[junaruga]

@tankf33der I have a question. How do you install clang on your Solaris 11? I could not find clang package on https://www.opencsw.org/get-it/packages/ . We have SPARC Solaris 10 and 11 servers where clang is not installed. I want to consider to install clang on the environments in the future if it is easy to install.

[tankf33der]

@tankf33der I have a question. How do you install clang on your Solaris 10 or 11? I could not find clang package on https://www.opencsw.org/get-it/packages/ . We have SPARC Solaris 10 and 11 servers where clang is not installed. I want to consider to install clang on the environments in the future if it is easy to install.

@junaruga
Solaris11 had LLVM6 package for many years via builtin standard pkg (IPS subsystem) and from version Oracle Solaris 11.4.30.88.3 Support Repository Update (Oracle Solaris 11.4 SRU 30.88.3) (Doc ID 2751881.1) Solaris11 has updated to LLVM11.
You must consider check pkgsrc to use in Solaris10 and 11 if you do not have active support plan from Oracle.

I am interested in learn something new and help you get LLVM, find me privately.

BTW, I gonna try compile ruby3 on IRIX too :)