superenv defaults to servile mode. In servile mode:
* If 'gcc' is called, then 'gcc' is run (we ignore HOMEBREW_CC)
* CFLAGS (optimizations) are not applied
* ARGV is not mangled (TODO though we should apply fixes)
* -I and -L environment is still forcibly inserted.
This fixes, eg. jack which was still broken with stdenv. Jack was broken because we set CC in stdenv, and Jack has a stupid build-system. Unsetting CC allowed Jack to find and use the gcc tool it so demanded, but (previously) we would then substitute clang under its nose. The configure still failed. In servile mode (llvm-)gcc is used and Jack compiles.
In normal circumstances clang would then be inserted again during the make phase. But Jack uses the niche-wag build tool that we don't support for setting the O HOMEBREW_CCCFG flag that disables servile mode.
This patch removes most of the settings for CC, CXX etc. because we are trying to be minimal. Then we force the compiler to Homebrew's choice underneath in superenv. We however leave LD because we prefer that build-systems use the c-compiler for linking, it generally works better (copiously tested), however when the build-system explicitly calls ld, we respect that. This gets around the ocaml bug in question, since somehow clang was crashing during link, but the ld tool itself (which is kind of clang, kind of llvm-gcc) is okay with this.
Also moved the setting of O (so that cc-args are refurbished) into a make wrapper. Not sure if this matter much, but seems more consistent.
The problem here now is though that the warnings only appear when compiling verbosely. But they should thus be visible if the build fails. Or if people are hunting for problems.
1. A minimal build environment, we don't set CFLAGS, CPPFLAGS, LDFLAGS, etc. the rationale being, the less that is set, the less variables we are introducing that can break builds.
2. A set of scripts that replace cc, ld, etc. and inject the -I, -L, etc. flags we need into the args passed to the build-tools.
Because we now have complete control over compiler instantiations we do a variety of clean-up tasks, like removing bad flags, enforcing universal builds and ensuring makefiles don't try to change the order of library and include paths from ones that work to ones that don't.
The previous ENV-system is still available when --env=std is specified.
superenv applies to Xcode >= 4.3 only currently.
